CN102847732A - Hot rolling spray cooling method for large cylinder - Google Patents

Abstract

The invention relates to a hot rolling spray cooling method for a large cylinder, which is characterized in that an upper spray device and a lower spray device are manufactured; after a large cylinder is rolled, the cylinder is clamped by an upper roller and a lower roller, so that the cylinder is rotated by the driving of frictional force; additionally, the lower spray device extends into the cylinder, and the upper spray device is arranged outside the cylinder; the length of cooling water pipes on the upper spray device and the lower spray device is regulated, so that a connecting line of all of the cooling water pipes on each spray device near the wall end of the cylinder forms a semicircle shape which is concentric with the cylinder; and additionally, the quantity ratio of the cooling water pipes on an upper spray collecting plate and a lower spray collecting plate of the upper spray device and the lower spray device and the flow ratio of cooling water are regulated, so as to cool the inner and outer surfaces of the large cylinder at the same cooling speed after rolling. The hot rolling spray cooling method has the advantages that the problem of uneven cooling of the traditional cylinder heat treatment is solved, the cooling efficiency is increased, the coefficient of heat transfer of the surface of the cylinder is increased on the initial stage of cooling, and the surface quality of the cylinder is greatly increased.

Description

A kind of large-scale shell ring hot rolling spraying cooling method

Technical field

The invention belongs to the cooling technology field, relate to a kind of for the spraying cooling method after the large-scale shell ring hot rolling shaping.

Background technology

Large-scale shell ring continuous rolling has the advantages such as precision is high, allowance is few, stock utilization is high, the interiors of products quality is good as a kind of emerging technique.The choosing and the control of process for cooling of the type of cooling after the hot rolling is the critical process step that guarantees large-scale shell ring product serviceability.Adopt traditional Technology for Heating Processing, when shell ring is carried out quench cooled, because the shell ring size is large, different parts on shell ring is axial can not cool off simultaneously, cooling has the regular hour poor, easily cause temperature distributing disproportionation even, thereby produce larger residual stress, cause shell ring axially and larger distortion is directly upwards arranged; Because shell ring from great, easily produces moderate finite deformation diametrically and becomes elliptical shape when quenching, reduced the dimensional accuracy of shell ring, and the shell ring performance is produced adverse influence.During again because of quench cooled, the shell ring surface easily produces steam blanket, affects the heat transfer of shell ring.In addition, the prior heat treatment process cost is high, is difficult to realize mass production, can not satisfy the domestic market to the wilderness demand of nuclear power, hydrogenation and coal liquefaction shell ring.Roll the efficient of rear cooling in order to improve large-scale shell ring, reduce and roll the cost of rear cooling, improve the mechanical property of shell ring, be necessary to study and adopt new process for cooling to replace traditional Technology for Heating Processing.

Spraying cooling is a kind of effective heat-transferring method, has high cooling capacity, is water to be pressurizeed into be similar to the disconnected shape or vaporific in slope, forms the drop bundle and impacts the object that is cooled.Existing spraying cooling method adopts synchronous spray cooling device cooling, and shell ring surfaces externally and internally temperature differs larger after the cooling, and inhomogeneous cooling is even.

Summary of the invention

The purpose of this invention is to provide a kind of large-scale shell ring hot rolling spraying cooling method that can solve the even problem of inhomogeneous cooling of traditional shell ring heat treatment appearance.

Technical scheme of the present invention is as follows:

Make one by upper water spray collection plate and vertical distribution at upper spray equipment and the lower spray equipment that the cooling water pipe on lower water spray collection plate consists of by lower water spray collection plate and vertical distribution that the cooling water pipe on the upper water spray collection plate consists of, after the rolling end of large-scale shell ring, on, bottom roll clamps shell ring with less drafts, shell ring is rotated under the drive of frictional force, same at present spray equipment extend into shell ring inside, upper spray equipment is outside relative with lower spray equipment at shell ring, in the adjusting, cooling water pipe length makes the line of the nearly shell ring wall end of all cooling water pipes on each spray equipment consist of the semicircle shape concentric with shell ring on the lower spray equipment, on adjusting simultaneously, lower spray equipment upper, the flow-rate ratio of the quantity of cooling water pipe ratio and cooling water realizes in the large-scale shell ring on the lower water spray collection plate, rolling of outer surface cooled off afterwards with cooling rate.

How accurately setting the flow-rate ratio of calculating upper and lower water spray collection plate cooling water in the method for the present invention, is to guarantee that the inside and outside surface film thermal conductance of shell ring is identical or close, realizes that the inside and outside surface of shell ring is with the key of cooling rate cooling.

By the analysis of spraying cooling mechanism as can be known, the impact velocity of current and the shock zone area under the nozzle have determined the size of convection transfer rate.If the angle that spray cooling device covers is θ, the shell ring wall thickness is B, and equivalent redius is R, and outer surface cooling arc length is L ₁, inner surface is L ₂, the quantity of surfaces externally and internally cooling water pipe is respectively n ₂, n ₁, see accompanying drawing 4

If spraying cooling water pipe is round nozzle, its heat flow density has following form

${\mathrm{hf}}_{\mathrm{lm}}={\mathrm{Cv}}_l^{0.5}{d}_c^{1.608}\mathrm{\Δ}{T}_{\mathrm{sat}}^{0.14}---\left(1\right)$

C in the formula---coefficient is by the degree of supercooling Δ T of liquid _SubDetermine Δ T _Sub=T _Sat-T _c, T _SatBe the saturation temperature point of cooling fluid, T _cBe coolant temperature, K

v _l---cooling fluid column impact speed, m/s

d _c---liquid-column impingement diameter, mm

Δ T _Sat---Δ T _Sat=T _s-T _Sat, T _sBe surface of steel plate temperature, K

Hf _Lm1, hf _Lm2---heat flow density, W/m ²

Make hf _Lm1=hf _Lm2, then have

${\mathrm{<figure-callout\; id="1"\; label="Cn\; l"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">Cn</figure-callout>}}_l^1{\mathrm{<figure-callout\; id="1"\; label="d\; c"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_c^1{\mathrm{DT}}_{\mathrm{sat}}^{0.14}={\mathrm{Cn}}_{l2}^{0.5}{d_{c2}}^{1.608}{\mathrm{DT}}_{\mathrm{sat}}^{0.14}---\left(2\right)$

V in the formula _L1, v _L2---the speed when upper and lower nozzle current arrive upper surface of steel plate, m/s

d _C1, d _C2---diameter when current arrive the steel plate upper and lower surface, mm

Can get

$\frac{v_{l1}}{v_{l2}}=\frac{d_{c2}^{3.216}}{{\mathrm{<figure-callout\; id="1"\; label="d\; c"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_c^1}---\left(3\right)$

And ${\mathrm{<figure-callout\; id="1"\; label="d\; c"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_c=\frac{L_1}{{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">n</figure-callout>}}_1},d_{c2}=\frac{L_2}{n_2},{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">L</figure-callout>}}_1=\mathrm{\&theta;}(R-\frac{B}{2}),L_2=\mathrm{\&theta;}(R+\frac{B}{2})$

According to the continuity equation of fluid, diameter became when current arrived the steel plate upper and lower surface again

$\begin{array}{cc}{\mathrm{<figure-callout\; id="1"\; label="d\; c"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_c=d_1\sqrt{v_1/v_{l1}}& d_{c2}=d_2\sqrt{v_2/v_{l2}}\end{array}----\left(4\right)$

Order $\frac{d_{c2}^{3.216}}{{\mathrm{<figure-callout\; id="1"\; label="d\; c"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_c^1}=k$

Then have

$\frac{v_{l1}}{v_{l2}}=k={\left[\frac{(R+\frac{B}{2})n_1}{(R-\frac{B}{2})n_2}\right]}^{3.216}---\left(5\right)$

Speed when upper and lower nozzle current arrive upper surface of steel plate is respectively

$v_{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">l</figure-callout>}1}=\sqrt{v_1^2+2g{H}_1}---\left(6\right)$

$v_{l2}=\sqrt{v_2^2-2g{H}_2}---\left(7\right)$

With formula (6), formula (7) is brought formula (5) into and is got

$\frac{\sqrt{v_1^2+2g{H}_1}}{\sqrt{v_2^2-2g{H}_2}}=k---\left(8\right)$

H in the formula ₁, H ₂---the distance of upper and lower cooling water pipe nozzle distance surface of steel plate, mm

v ₁, v ₂---the water velocity of upper and lower cooling water pipe jet expansion is respectively

${\mathrm{<figure-callout\; id="1"\; label="v"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">v</figure-callout>}}_1=\frac{4q}{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_1^2}---\left(9\right)$

$v_2=\frac{4R_{1}q}{\mathrm{\&pi;}{d}_2^2}---\left(10\right)$

Q in the formula---upper water spray collection plate cooling water pipe nozzle flow

R ₁---upper and lower water spray collection plate cooling water pipe nozzle flow ratio

d ₁, d ₂---upper and lower water spray collection plate cooling water pipe nozzle diameter, mm

Simultaneous formula (5), formula (8), formula (9) and formula (10) can solve flow-rate ratio R ₁Compare n with cooling water pipe quantity ₁/ n ₂Between relation and R ₁Value.

Its pass is $\frac{\sqrt{{\left(\frac{4q}{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HDA00002031248700011.png"\; state="\{\{state\}\}">d</figure-callout>}}_1^2}\right)}^2+2g{H}_1}}{\sqrt{{\left(\frac{4q{R}_1}{\mathrm{\&pi;}{d}_2^2}\right)}^2-2g{H}_2}}={\left[\frac{(R+\frac{B}{2})n_1}{(R-\frac{B}{2})n_2}\right]}^{3.216}---\left(11\right)$

By foregoing as can be known, can adjust jet density and recently realize the identical or close of the inside and outside surperficial convection transfer rate of shell ring with the quantity of cooling water pipe.

Method of the present invention changes the cooled region area by the quantity of the cooling water pipe of the upper and lower water spray collection plate of adjusting;

Method of the present invention changes the length of cooling arc by the length of the cooling water pipe of the upper and lower water spray collection plate of adjusting;

Method of the present invention is accurately calculated the inside and outside surperficial convection transfer rate of shell ring by quantity and the length of the cooling water pipe of the upper and lower water spray collection plate of adjusting, realizes the rear cooling of rolling of different size shell ring.

The characteristics of large-scale shell ring hot rolling spraying cooling method of the present invention are: 1, shell ring cools off while rotating, and has corrected the ovality that causes because of residual stress, has guaranteed the dimensional accuracy of shell ring; 2, regulate the water yield on the inside and outside surface of shell ring, make the inside and outside surperficial cooling rate of shell ring identical, avoided the appearance of surface warp, guaranteed the surface quality of shell ring; 3, compare the speed with cooling and the advantage such as uniformity is high, production efficiency is high, integrated cost is low with original shell ring Technology for Heating Processing; 4, compare with existing spraying cooling method, the method highly versatile, can realize different size shell ring roll rear cooling; Upper and lower water spray collection plate cooling water inflow can be by changing the quantity ratio realization of cooling water pipe, and the water yield is more simple than regulation and control.

Beneficial effect of the present invention:

The present invention preferably resolves the even difficult problem of large-scale shell ring inhomogeneous cooling, and the injection shell ring surface of cooling water approximate vertical has increased with the shell ring direct contact surface and amassed, and is easy to break through the steam blanket on shell ring surface, thereby has eliminated the impact that steam blanket conducts heat on shell ring.After adopting this method, can realize that not only surfaces externally and internally cools off, effectively removes the oxide skin on shell ring surface with cooling rate, improve cooling effectiveness, and increased the coefficient of heat transfer on shell ring surface in the cooling starting stage, the surface quality of raising shell ring that can be by a relatively large margin.

Description of drawings

Fig. 1 is spraying cooling schematic diagram after the medium-and-large-sized shell ring hot rolling of method of the present invention;

Fig. 2 is upper spray equipment schematic diagram in the method for the present invention;

Fig. 3 is lower spray equipment schematic diagram in the method for the present invention;

Fig. 4 is the relation between each variable of spray equipment in the method for the present invention;

Fig. 5 is that the water yield of upper water spray collection plate cooling water pipe in the method for the present invention compares changing trend diagram;

Fig. 6 be in the method for the present invention the water yield than with the graph of a relation of the quantity ratio of cooling water pipe.

Among the figure: 1, upper spray equipment, 2, lower spray equipment, 3, topping roll, 4, bottom roll, 5, guide roller, 6, shell ring, 7, upper water spray collection plate, 8, the cooling water pipe of upper water spray collection plate, 9, lower water spray collection plate, 10, the cooling water pipe of lower water spray collection plate.

The specific embodiment

Embodiment

Method 1: by the spraying cooling method that adopts the present invention to propose, large-scale shell ring is rolled rear spraying cooling simulate.The uniformity of shell ring surfaces externally and internally Temperature Distribution after analysis employing the method.

The specification of the shell ring that adopts: external diameter: d ₁=5830mm, internal diameter: d ₂=4796mm, width: 2680mm; The rotating speed of top and bottom rolls is 0.3rad/s.The base attribute of material: yield limit: 58MPa; Elastic modelling quantity: 90000MPa; Poisson's ratio: 0.3; Its surplus such as density, specific heat is the function of temperature.The shell ring rotating speed is 0.1rad/s by calculating as can be known, and setting its initial temperature is 900 ℃.The circular arc that the height of regulating cooling water pipe makes its end is concentric and 50mm apart with shell ring, and simultaneously, the angle in spraying cooling arc and the shell ring center of circle is 60 to spend its schematic diagram such as Fig. 1.

Upper and lower water spray collection plate cooling water pipe diameter is identical, gets water spray and integrates the jet density of plate cooling water as 160m ³/ h calculates as can be known through this method that water yield ratio is 1.8, integrates the jet density of plate cooling water as 288m thereby calculate lower water spray ³/ h.According to the quantity ratio of cooling water pipe and the relation between flow-rate ratio, the quantity ratio of upper and lower water spray collection plate cooling water pipe is 0.55 as can be known.

Get arbitrarily 2 points on the shell ring surfaces externally and internally, be designated as A point, B point, analyze its temperature temporal evolution trend as shown in table 1

Table 1 shell ring surfaces externally and internally node temperature temporal evolution trend

Time/s	The number of turns/q	Outer surface/℃	Inner surface/℃	The temperature difference/℃
					62.8	1	145.723	141.118	4.605
314	5	127.162	124.037	3.125
					628	10	105.285	102.962	2.323
942	15	91.249	88.955	2.294
					1257.6	20	83.556	81.619	1.937
1570	25	72.934	70.851	2.083
					1884	30	69.604	66.902	2.702

As can be known from the above table, adopt spraying cooling mode of the present invention, the inside and outside surface temperature of shell ring is more or less the same, and to become stepped slow decreasing, maximum temperature difference be 4.605 ℃, and cooling evenly.

Method 2: adopt traditional quenching technical cooling, in like manner get A point and B point on the inside and outside surface of shell ring, record its temperature temporal evolution situation as shown in table 2

Table 2 shell ring surfaces externally and internally node temperature temporal evolution trend

Time/s	The number of turns/q	Outer surface/℃	Inner surface/℃	The temperature difference/℃
					62.8	1	195.72	142.11	53.61
314	5	187.16	165.03	22.13

628	10	155.28	133.96	21.32
					942	15	120.24	100.95	19.29
1257.6	20	109.55	95.61	13.94
					1570	25	89.93	81.85	8.08
1884	30	74.60	63.90	11.7

Adopt as can be known from the above table quenching technical, cool off when initial the shell ring cooling slowly because the effect of steam blanket so that between the 62.8-314s surface temperature change little.Prolong in time, steam blanket breaks gradually and the violent agitation heat exchange of water sharply descends the shell ring surface temperature.Maximum temperature difference is 53.61 ℃, and inhomogeneous cooling is even.

Method 3: adopt existing synchronous spray cooling device cooling, in like manner get A point and B point on the inside and outside surface of shell ring, record its temperature and ask that at any time situation of change is as shown in table 3

The surfaces externally and internally node temperature was asked variation tendency at any time after table 3 shell ring quenched

Time/s	The number of turns/q	Outer surface/℃	Inner surface/℃	The temperature difference/℃
					62.8	1	204.02	190.28	13.74
314	5	173.26	158.74	14.52
					628	10	198.30	170.29	28.01
942	15	124.92	115.49	9.43
					1257.6	20	109.65	100.39	9.26
1570	25	88.29	73.72	14.57
					1884	30	71.38	59.17	12.21

As can be known from the above table, adopt existing synchronous spray cooling device cooling, the inside and outside surface temperature of shell ring differs larger, and maximum temperature difference is 28.01 ℃.

Method 1, method 2 and method 3 are compared and can find out, the spraying cooling method that the present invention proposes can effectively evenly be cooled off shell ring, and simple to operate, reduced the cycle that shell ring is produced greatly.

Claims (5)

1. one kind large-scale shell ring hot rolling spraying cooling method, it is characterized in that: make one by upper water spray collection plate and vertical distribution at upper spray equipment and the lower spray equipment that the cooling water pipe on lower water spray collection plate consists of by lower water spray collection plate and vertical distribution that the cooling water pipe on the upper water spray collection plate consists of, after the rolling end of large-scale shell ring, on, bottom roll clamps shell ring with less drafts, shell ring is rotated under the drive of frictional force, same at present spray equipment extend into shell ring inside, upper spray equipment is outside relative with lower spray equipment at shell ring, in the adjusting, cooling water pipe length makes the line of the nearly shell ring wall end of all cooling water pipes on each spray equipment consist of the semicircle shape concentric with shell ring on the lower spray equipment, on adjusting simultaneously, lower spray equipment upper, the flow-rate ratio of the quantity of cooling water pipe ratio and cooling water realizes in the large-scale shell ring on the lower water spray collection plate, rolling of outer surface cooled off afterwards with cooling rate.

2. large-scale shell ring hot rolling spraying cooling method according to claim 1, it is characterized in that: cooling water inflow compares R after the rolling end of shell ring ₁Compare n with cooling water pipe quantity ₁/ n ₂Between the pass be:

$\frac{\sqrt{{\left(\frac{4q}{\mathrm{\&pi;}{d}_1^2}\right)}^2+2g{H}_1}}{\sqrt{{\left(\frac{4q{R}_1}{\mathrm{\&pi;}{d}_2^2}\right)}^2-2g{H}_2}}={\left[\frac{(R+\frac{B}{2})n_1}{(R-\frac{B}{2})n_2}\right]}^{3.216}.$

3. large-scale shell ring hot rolling spraying cooling method according to claim 2 is characterized in that: the quantity of the cooling water pipe by regulating upper and lower water spray collection plate changes the cooled region area.

4. large-scale shell ring hot rolling spraying cooling method according to claim 2 is characterized in that: the length of the cooling water pipe by regulating upper and lower water spray collection plate changes the length of cooling arc.

5. according to claim 3 or 4 described large-scale shell ring hot rolling spraying cooling methods, it is characterized in that: quantity and the length of the cooling water pipe by regulating upper and lower water spray collection plate, accurately calculate the inside and outside surperficial convection transfer rate of shell ring, realize the rear cooling of rolling of different size shell ring.

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