CN102847732B - Hot rolling spray cooling method for large cylinder - Google Patents

Abstract

The invention relates to a spray cooling method for hot rolling of a large-scale drum section, which is characterized in that upper and lower spray devices are made, and after the rolling of the large-scale drum segment is completed, the upper and lower rolls clamp the drum segment so that the drum segment is At the same time, the lower spraying device extends into the inside of the cylinder section, and the upper spraying device is outside the cylinder section. Adjust the length of the cooling water pipes on the upper and lower spraying devices so that all the cooling water pipes on each spraying device are close to the cylinder. The connection line at the end of the section wall forms a semicircle concentric with the barrel section, and at the same time adjust the ratio of the number of cooling water pipes and the flow rate ratio of the cooling water on the upper and lower spray collector plates of the upper and lower spray devices to realize the inner and outer of the large barrel section The surface is cooled at the same cooling rate after rolling. Its advantages are: it solves the problem of non-uniform cooling in the traditional heat treatment of the shell joint, and this method not only improves the cooling efficiency, but also increases the heat transfer coefficient of the shell joint surface in the initial stage of cooling, and greatly improves the surface quality of the shell joint .

Description

A Spray Cooling Method for Hot Rolling of Large Scale Sections

technical field

The invention belongs to the technical field of cooling, and relates to a spray cooling method used for large-scale tubular sections after hot rolling and forming.

Background technique

As a new technology, the continuous rolling of large barrel segments has the advantages of high precision, less machining allowance, high material utilization rate, and good internal quality of products. The selection of cooling method after hot rolling and the control of cooling process are the key process steps to ensure the performance of large-scale drum products. When the traditional heat treatment process is used to quench and cool the barrel section, due to the large size of the barrel section, different parts in the axial direction of the barrel section cannot be cooled at the same time, and there is a certain time difference in cooling, which will easily cause uneven temperature distribution, resulting in large Residual stress causes large deformation of the cylinder joint in the axial and radial directions; due to the self-heaviness of the cylinder joint, it is easy to produce large deformation in the radial direction during quenching and become an elliptical shape, which reduces the dimensional accuracy of the cylinder joint and affects the cylinder joint. energy saving can be adversely affected. And because of quenching and cooling, the surface of the cylinder joint is easy to produce a steam film, which affects the heat transfer of the cylinder joint. In addition, the cost of traditional heat treatment process is high, it is difficult to achieve mass production, and it cannot meet the large demand for nuclear power, hydrogenation and coal liquefaction cylinders in the domestic market. In order to improve the efficiency of post-rolling cooling of large-scale tube segments, reduce the cost of post-rolling cooling, and improve the mechanical properties of tube segments, it is necessary to study and adopt a new cooling process to replace the traditional heat treatment process.

Spray cooling is an effective heat transfer method with high cooling capacity. It pressurizes water to form a slope or mist, and forms a droplet beam to impact the object to be cooled. The existing spray cooling method uses a synchronous spray cooling device for cooling. After cooling, the temperature difference between the inner and outer surfaces of the cylinder section is large, and the cooling is uneven.

Contents of the invention

The purpose of the present invention is to provide a spray cooling method for hot rolling of large-scale barrel sections which can solve the problem of uneven cooling in traditional heat treatment of barrel sections.

Technical scheme of the present invention is as follows:

Make an upper sprinkler device consisting of an upper spray collector plate and cooling water pipes vertically distributed on the upper spray collector plate and a lower sprinkler device composed of a lower spray collector plate and cooling water pipes vertically distributed on the lower spray collector plate Spraying device, after the rolling of the large barrel section, the upper and lower rollers clamp the barrel section with a small reduction, so that the barrel section rotates under the drive of friction, and at the same time, the lower spray device extends into the inside of the barrel section 1. The upper spraying device is opposite to the lower spraying device outside the cylinder section. Adjust the length of the cooling water pipes on the upper and lower spraying devices so that the connection line of all cooling water pipes on each spraying device near the wall end of the cylinder section is concentric with the cylinder section. At the same time, adjust the quantity ratio of the cooling water pipes and the flow ratio of the cooling water on the upper and lower spray collecting plates of the upper and lower spraying devices to realize the same cooling speed cooling of the inner and outer surfaces of the large barrel section after rolling.

In the method of the present invention, how to accurately set and calculate the flow rate ratio of the cooling water of the upper and lower spray collector plates is to ensure that the heat transfer coefficients of the inner and outer surfaces of the barrel section are the same or similar, and realize the cooling of the inner and outer surfaces of the barrel section at the same cooling rate. The essential.

According to the analysis of the spray cooling mechanism, the impact velocity of the water flow and the area of the impact area directly below the nozzle determine the convective heat transfer coefficient. Suppose the angle covered by the spray cooling device is θ, the wall thickness of the cylinder section is B, the equivalent radius is R, the cooling arc length of the outer surface is L ₁ , the inner surface is L ₂ , and the numbers of cooling water pipes on the inner and outer surfaces are n ₂ , n ₁ , see attached drawing 4

Assuming that the spray cooling water pipe is a circular nozzle, its heat flux has the following form

${\mathrm{<span\; class="notranslate">\; hf</span>}}_{\mathrm{<span\; class="notranslate">\; lm</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}}^{\mathrm{<span\; class="notranslate">\; 0.5</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}^{\mathrm{<span\; class="notranslate">\; 1.608</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; sat</span>}}^{\mathrm{<span\; class="notranslate">\; 0.14</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, C—coefficient, determined by the subcooling degree ΔT _sub of the liquid, ΔT _sub =T _sat —T _c , T _sat is the saturation temperature point of the cooling liquid, T _c is the temperature of the cooling liquid, K

ν _l ——Impact velocity of coolant column, m/s

d _c ——diameter of liquid column impact, mm

ΔT _sat ——ΔT _sat =T _s —T _sat , T _s is the steel plate surface temperature, K

hf _lm1 , hf _lm2 ——heat flux density, W/m ²

Let hf _lm1 ＝hf _lm2 , then we have

$\mathrm{<span\; class="notranslate">\; C</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 0.5</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}^{\mathrm{<span\; class="notranslate">\; 1.608</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; sat</span>}}^{\mathrm{<span\; class="notranslate">\; 0.14</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; C</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 0.5</span>}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}^{\mathrm{<span\; class="notranslate">\; 1.608</span>}}{\mathrm{<span\; class="notranslate">\; \&Delta;T</span>}}_{\mathrm{<span\; class="notranslate">\; sat</span>}}^{\mathrm{<span\; class="notranslate">\; 0.14</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula, v _l1 and v _l2 ——the speed when the upper and lower nozzles reach the upper surface of the steel plate, m/s

d _c1 , d _c2 ——diameter when the water flow reaches the upper and lower surfaces of the steel plate, mm

Available

$\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 3.216</span>}}}{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 3.216</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

and $d_{c1}=\frac{L_1}{{\mathrm{no}}_1},d_{c2}=\frac{L_2}{{\mathrm{no}}_2},L_1=\mathrm{\&theta;}(R-\frac{B}{2}),L_2=\mathrm{\&theta;}(R+\frac{B}{2})$

According to the continuity equation of the fluid, when the water flow reaches the upper and lower surfaces of the steel plate, the diameter becomes

${\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\sqrt{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\sqrt{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

make $\frac{d_{c2}^{3.216}}{d_{c1}^{3.216}}=k$

then there is

$\frac{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; B</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; B</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; 3.216</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The velocities of the water flow from the upper and lower nozzles when they reach the upper surface of the steel plate are respectively

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\sqrt{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Put formula (6), formula (7) into formula (5) to get

$\frac{\sqrt{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}}{\sqrt{{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; g</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

In the formula, H ₁ , H ₂ ——the distance between the upper and lower cooling water pipe nozzles and the steel plate surface, mm

v ₁ , v ₂ ——water flow velocity at the nozzle outlet of the upper and lower cooling water pipes, respectively

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

In the formula, q——the nozzle flow rate of the cooling water pipe of the upper spray water collecting plate

R ₁ ——The flow rate ratio of the cooling water pipe nozzles of the upper and lower water spray collector plates

d ₁ , d ₂ ——The nozzle diameter of the cooling water pipe of the upper and lower water spray collector plates, mm

Simultaneous formula (5), formula (8), formula (9) and formula (10) can solve the relationship between the flow ratio R ₁ and the number ratio of cooling water pipes n ₁ /n ₂ and the value of R ₁ .

Its relationship is $\frac{\sqrt{{\left(\frac{4q}{\mathrm{\&pi;}{d}_1^2}\right)}^2+2g{h}_1}}{\sqrt{{\left(\frac{4q{R}_1}{\mathrm{\&pi;}{d}_2^2}\right)}^2-2g{h}_2}}={\left[\frac{(R+\frac{B}{2}){\mathrm{no}}_1}{(R-\frac{B}{2}){\mathrm{no}}_2}\right]}^{3.216}---\left(11\right)$

From the above content, it can be seen that the ratio of the water flow density to the number of cooling water pipes can be adjusted to achieve the same or similar convective heat transfer coefficients between the inside and outside of the cylinder section.

The method of the present invention changes the area of the cooling area by adjusting the number of cooling water pipes on the upper and lower water spray collecting plates;

The method of the present invention changes the length of the cooling arc by adjusting the length of the cooling water pipes of the upper and lower water spray collecting plates;

The method of the invention adjusts the quantity and length of the cooling water pipes of the upper and lower water-spraying collecting plates, accurately calculates the convective heat transfer coefficients inside and outside the barrel section, and realizes post-rolling cooling of the barrel sections with different specifications.

The characteristics of the spray cooling method for large-scale barrel section hot rolling of the present invention are: 1. The barrel section is cooled while rotating, which corrects the ellipticity caused by residual stress and ensures the dimensional accuracy of the barrel section; 2. Adjusts the inside of the barrel section, The amount of water on the outer surface makes the cooling rate of the inner and outer surfaces of the barrel joint the same, avoiding the appearance of surface warping and ensuring the surface quality of the barrel joint; 3. Compared with the original heat treatment process of the barrel joint, it has cooling speed and uniformity 4. Compared with the existing spray cooling method, this method has strong versatility, and can realize the post-rolling cooling of different specifications of barrel sections; the upper and lower water spray collector plates The cooling water volume can be realized by changing the quantity ratio of the cooling water pipes, and the water volume ratio regulation is simple and easy.

Beneficial effects of the present invention:

The invention better solves the problem of uneven cooling of large-scale barrel joints. The cooling water is sprayed approximately vertically on the surface of the barrel joint, which increases the direct contact area with the barrel joint and easily breaks through the steam film on the surface of the barrel joint, thereby eliminating the steam film. Influence on the heat transfer of the barrel section. After adopting this method, not only can the inner and outer surfaces be cooled at the same cooling rate, effectively remove the scale on the surface of the cylinder section, and improve the cooling efficiency, but also increase the heat transfer coefficient of the surface of the cylinder section in the initial stage of cooling, which can be greatly improved Improve the surface quality of barrel joints.

Description of drawings

Fig. 1 is a schematic diagram of spraying and cooling after hot rolling of large-scale drum section in the method of the present invention;

Fig. 2 is a schematic diagram of upper spraying device in the method of the present invention;

Fig. 3 is a schematic diagram of the lower spraying device in the method of the present invention;

Fig. 4 is the relationship between each variable of spray device in the method of the present invention;

Fig. 5 is the change trend diagram of the water volume ratio of the cooling water pipe of the upper spray collector plate in the method of the present invention;

Fig. 6 is a graph showing the relationship between the ratio of water volume and the ratio of the number of cooling water pipes in the method of the present invention.

Detailed ways

Example

Method 1: By adopting the spray cooling method proposed by the present invention, the spray cooling after rolling of the large-scale barrel section is simulated. After adopting this method, the uniformity of temperature distribution on the inner and outer surfaces of the cylinder section is analyzed.

Specifications of the barrel joints used: outer diameter: d ₁ =5830mm, inner diameter: d ₂ =4796mm, width: 2680mm; the rotational speed of the upper and lower rollers is 0.3rad/s. The basic properties of the material: yield limit: 58MPa; elastic modulus: 90000MPa; Poisson's ratio: 0.3; the rest of the density, specific heat, etc. are functions of temperature. Through calculation, it can be known that the rotational speed of the barrel joint is 0.1rad/s, and its initial temperature is set at 900°C. Adjust the height of the cooling water pipe so that the arc at the end is concentric with the barrel section and the distance is 50 mm. At the same time, the angle between the spray cooling arc and the center of the barrel section is 60 degrees. The schematic diagram is shown in Figure 1.

The cooling water pipes of the upper and lower spray collectors have the same diameter, and the flow density of the cooling water of the upper spray collector is 160m ³ /h. After calculation by this method, the water volume ratio is 1.8, and thus the cooling water flow rate of the lower spray collector is calculated. The water flow density is 288m ³ /h. According to the relationship between the number ratio of the cooling water pipes and the flow ratio, it can be known that the number ratio of the cooling water pipes of the upper and lower spray collector plates is 0.55.

Randomly take two points on the inner and outer surfaces of the cylinder joint, which are recorded as point A and point B, and analyze the temperature change trend with time, as shown in Table 1

Table 1. Time-varying trend of temperature at inner and outer surface nodes of barrel joints

time/s Number of laps/q External surface/℃ Inner surface/℃ 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

It can be seen from the above table that, with the spray cooling method of the present invention, the temperature difference between the inner and outer surfaces of the cylinder section is not large, and the temperature decreases slowly in a stepwise manner. The maximum temperature difference is 4.605°C, and the cooling is uniform.

Method 2: Use the traditional quenching process to cool, similarly take points A and B on the inner and outer surfaces of the barrel joint, and record the temperature change with time, as shown in Table 2

Table 2. Time-varying trend of temperature at inner and outer surface nodes of barrel joints

time/s Number of laps/q External surface/℃ Inner surface/℃ 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

It can be seen from the above table that the quenching process is adopted, and the cooling of the cylinder section is slow at the beginning of cooling. Due to the effect of the steam film, the surface temperature does not change much between 62.8-314s, and there is a tendency for the temperature to rise at 628s. As time goes on, the steam film gradually breaks and the strong boiling heat exchange of water causes the surface temperature of the cylinder section to drop sharply. The maximum temperature difference was 53.61°C, and the cooling was uneven.

Method 3: Use the existing synchronous spray cooling device to cool, similarly take points A and B on the inner and outer surfaces of the barrel section, and record the temperature change with time, as shown in Table 3

Table 3 Change trend of inner and outer surface joint temperature with time after quenching of barrel joint

time/s Number of laps/q External surface/℃ Inner surface/℃ 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

It can be seen from the above table that with the existing synchronous spray cooling device for cooling, the temperature difference between the inner and outer surfaces of the cylinder section is relatively large, and the maximum temperature difference is 28.01°C.

Comparing method 1, method 2 and method 3, it can be seen that the spray cooling method proposed by the present invention can effectively cool the barrel section uniformly, and is easy to operate, greatly reducing the production cycle of the barrel section.

Claims (2)

1. A method for spraying and cooling the hot-rolled large-scale barrel joints, which is characterized in that: make an upper spraying device made of an upper spraying water collecting plate and a cooling water pipe vertically distributed on the upper spraying water collecting plate and a lower spraying water collecting plate The lower spraying device is composed of the water collecting plate and the cooling water pipes vertically distributed on the lower spraying water collecting plate. Driven by the friction force to rotate, at the same time, the lower spray device extends into the inside of the cylinder section, and the upper spray device is opposite to the lower spray device outside the cylinder section. Adjust the length of the upper cooling water pipe of the upper and lower spray devices so that each spray The connection line of all the cooling water pipes on the device near the wall end of the cylinder section forms a semicircle concentric with the cylinder section, and at the same time adjust the number ratio of the cooling water pipes and the flow ratio of the cooling water on the upper and lower spray water collecting plates of the upper and lower spray devices , to realize the cooling at the same cooling rate after rolling of the inner and outer surfaces of the large-scale barrel section; the relationship between the cooling water volume ratio R ₁ and the cooling water pipe number ratio n ₁ /n ₂ after the rolling of the barrel section is finished is: In the formula: q is the nozzle flow rate of the cooling water pipe of the upper spray collector plate; R ₁ is the flow rate ratio of the nozzles of the cooling water pipe of the upper spray collector plate and the lower water collector plate; d ₁ and d ₂ are the nozzle diameters of the cooling water pipe nozzles of the upper and lower spray collector plate; H ₁ , H ₂ are the distances between the nozzles of the upper and lower cooling water pipes and the surface of the steel plate; n ₁ , n ₂ are the numbers of cooling water pipes on the outer surface and inner surface respectively; B is the wall thickness of the barrel section; R is the equivalent radius of the barrel section ; By adjusting the number of cooling water pipes of the upper and lower water spray collector plates, the area of the cooling area is changed; by adjusting the length of the cooling water pipes of the upper and lower water spray collector plates, the length of the cooling arc is changed. 2. The spray cooling method for hot-rolled large-scale barrel section according to claim 1, characterized in that: by adjusting the number and length of the cooling water pipes of the upper and lower water spray collector plates, the convective flow inside and outside the barrel section can be accurately calculated The heat transfer coefficient realizes the post-rolling cooling of barrel sections of different specifications.