CN2628171Y - Local strengthening heating apparatus before tapping of hot-rolled billet - Google Patents

Abstract

The utility model relates to a partial strengthening heating device for hot rolled steel billet before discharged, is characterized in that: the end of even heating section of heating furnace is provided with a partial strengthening heating zone or a partial strengthening heating room, at least a pair of burner is arranged at the two sides of wall or ceiling of the partial strengthening heating zone or the partial strengthening heating room, strengthening heating for the steel billet that finished even heating and is going to discharge at the 200 to 300mm length partial scale of both ends make the temperature of partial zone higher 80 to 120 DEG C than the even heating section with 20 to 30 seconds heating. The utility model has the advantages of reducing the difference in surface temperature of steel billet along the direction of steel billet length before entered the rolling machine, improving the evenness rolling temperature, the rolling quality of products and the production efficiency of rolling machine, reducing the rejection rate and the production cost.

Description

The hot rolling steel billet preceding local strengthening heater of coming out of the stove

Technical field

The utility model relates to a kind of hot rolling steel billet and heats, local strengthening heating and device before particularly a kind of hot rolling steel billet is come out of the stove.

Background technology

Hot rolling of steel billet at first need heat in heating furnace.Existing Large-scale Heater, furnace type structure is made up of syllogic or multisection type.Go into stove to the order of coming out of the stove by steel billet, divide preheating section, bringing-up section, soaking zone (syllogic) or preheating section, first bringing-up section, second bringing-up section, soaking zone (multisection type) is formed.See figure (1), (2).Preheating section does not generally have heating plant (promptly burn chew), and steel billet is reverse and go with the high-temperature flue gas that flows out from bringing-up section, and high-temperature flue gas is preheated to steel billet about 550 ℃.Steel billet elasticity after the preheating reduces greatly, and plasticity strengthens greatly, so after advancing bringing-up section, can be rapidly heated, reduces heat time heating time; For the steel billet that guarantees to come out of the stove meets the requirements (being generally less than 50 ℃) along the internal and external temperature of thickness direction, by technological requirement, the steel billet after the Fast Heating needs soaking in soaking zone, to reduce the temperature difference at billet surface and center.It is uniformly that such heating cycle and furnace type structure make the billet surface temperature of coming out of the stove, and steel billet inside and outside (surface is to the center) temperature difference is not more than 50 ℃, meets the requirement of technology.Yet steel billet is delivered in the milling train process at roller-way, because heat radiation causes the uniform steel billet of tapping temperature to become inhomogeneous to milling train.Theoretical calculating with actual measurement shows that all fed distance is long more, and rollgang surrounding enviroment intensity of cooling is big more, and is inhomogeneous more during the steel billet feed mill.Inhomogeneities mainly appears at steel billet two ends along its length, through field measurement 40～50 ℃ (slabs), the temperature difference of 50～70 ℃ (square billets) can be arranged.Such temperature difference steel grade (silicon steel etc.) higher to the rolling temperature uniformity requirement can cause the rolling quality problem, even the difficulty of can nipping (as square billet tandem rolling etc.), directly influences steel rolling production.And at present, still do not have a kind of device that can address this problem.

Summary of the invention

The purpose of this utility model is in order to reduce the surface temperature difference of continuous casting steel billet at feed mill forward position steel billet length direction, improves the rolling temperature uniformity, provide a kind of hot rolling steel billet to come out of the stove before the local strengthening heater.

The technical solution of the utility model be based on that the steel billet tapping temperature distributes and the time of steel billet local strengthening heating in stove calculate the steel billet two ends along in the subrange of length 200-300mm, heating-up temperature needs these data than 4～10 ℃ of other steel billet scopes raisings, the local strengthening thermal treatment zone of setting up at heating furnace soaking zone end or set up the local strengthening heating clamber, in the local strengthening thermal treatment zone or local strengthening heating clamber both walls or furnace roof both sides be equipped with 1 pair of burning at least and chew, heating is strengthened at the steel billet two ends that are about to come out of the stove.

Adopt the utility model, reduce the surface temperature difference of continuous casting steel billet at feed mill forward position steel billet length direction, improve the rolling temperature uniformity, improve the product rolling quality, reduce percent defective, rolling rate improves, and reduces production costs.

Description of drawings

Fig. 1 is the slab that is of a size of 10000 * 2000 * 230mm temperature distribution history along its length;

Fig. 2 is the square billet that is of a size of 11000 * 140 * 140mm temperature distribution history along its length;

Fig. 3 need strengthen the heated perimeter schematic diagram for the slab two ends;

Fig. 4 need strengthen the heated perimeter schematic diagram for the square billet two ends;

Fig. 5 is a local strengthening thermal treatment zone structural representation;

Fig. 6 is the A-A profile of Fig. 5;

Fig. 7 is a local strengthening heating clamber structural representation;

Fig. 8 is the A-A profile of Fig. 7.

The specific embodiment

This device is based on calculating and the steel billet Time Calculation that local strengthening heats in stove that the steel billet tapping temperature distributes and requires, and details are as follows:

1, the calculating of tapping temperature distribution requirement

Steel billet tapping temperature distribution requirement can be pressed the biographies thermal model and be obtained through numerical computations:

$\mathrm{\λ}\frac{{\∂}^{2}T}{\∂X^2}-\frac{\mathrm{\ϵ\σ}}{b_1}(T^4-T_{\∞}^4)=\mathrm{\ρc}\frac{\∂T}{\∂t}$

$X=0---\frac{\∂T}{\∂X}=0$

$X=L,-\mathrm{\λ}\frac{\∂T}{\∂X}=\mathrm{\ϵ\σ}(T^4-T_{\∞}^4)$

T＝τ T＝f(χ)

Wherein λ, ρ, c, ε are respectively thermal conductivity factor, density, specific heat and the blackness of blank, and σ is the Si Difen constant, b ₁Square billet is got half that size dimension, slab are got gauge, and T is a steel billet Temperature Distribution along its length, and X is a steel billet coordinate along its length, T _∞Be environment temperature, τ be steel billet from the required transmission time of the rolling mill of coming out of the stove, f (χ) is the τ Temperature Distribution of steel billet constantly.

Calculated example: is 140 * 140mm to length for 12m, cross section ²45 ^#Wire blank, the Temperature Distribution when getting it to milling train is: T=1000 ℃ at x=0 place; T=960 ℃ at x=6m place.The situation that gets blank end temperature and adjacent regions temperature as calculated is as follows: (℃)

Transmit cool time	25 seconds	35 seconds	40 seconds	45 seconds
					The blank end temperature	988	1001	1007	1014
Temperature from end 200mm place	984	994	998	1004

Can obtain in transmission is 25～45 seconds time range cool time from the data of last table, the blank end temperature should be than high 4～10 ℃ from the temperature at end 200mm place.

2, strengthen the Time Calculation of heating

Steel billet following heat transfer model of time of local strengthening heating in stove calculates

$\mathrm{\ρcLS}\frac{\mathrm{dT}}{\mathrm{d\τ}}\mathrm{\α}(T_{\∞}-T)$

τ＝0 T＝T ₁

In the following formula ρ, c as described above, L=200mm, S are the blank sectional area, α is the rad equivalent coefficient of heat transfer, T _∞Be local strengthening heating furnace gas temperature, T is the blank end temperature, and τ is local strengthening heat time heating time, T ₁Temperature when leaving soaking zone for blank.

Calculated example: the temperature the when temperature of getting the L=200mm place is left soaking zone as blank, T _∞Get 1100 ℃ by experience, the time following (second) that the local strengthening heating is required

Temperature when blank leaves soaking zone (℃)	984	994	998	1004
					The time that the local strengthening heating is required	20	25	27	30

Obtain steel billet two ends these data based on aforementioned calculation along 4～10 ℃ of the raisings of length 200-300mm, set up a local strengthening thermal treatment zone or local strengthening heating clamber at the soaking zone end, to steel billet two ends 200-300mm, indicate shown in the oblique line part as Fig. 3, Fig. 4, subrange is strengthened heating, make temperatures at localized regions (being the regional area furnace temperature) be approximately higher than 80～120 ℃ of soaking zone furnace temperature, 20～30 seconds heat time heating times.

Enforcement of the present utility model is example with the three-stage heating furnace, and as Fig. 5, shown in Figure 7, heating furnace is made up of preheating section 1, bringing-up section 2, soaking zone 3, the hot rolling steel billet preceding local strengthening heater of coming out of the stove, and its characteristics are:

1, sets up a local strengthening thermal treatment zone 4 at heating furnace soaking zone 3 ends, promptly will go out the fire door both walls,, be equipped with 1 pair of burning at least and chew 5, finishing the steel billet two ends reinforcement heating that soaking is about to come out of the stove according to the steel billet kind at the stove soaking zone.Under the preceding topic that does not change the existing type of furnace, the both walls (from 0.3～2 meter of outlet) that is about to out fire door at the stove soaking zone is reconstructed into half garden arc indent side wall 6 with the stove inwall, as Fig. 5, shown in Figure 6, and in the indent furnace wall of both sides, respectively be equipped with 1 when square billet (heating), 2～3 burnt and chew (during the heating slab).To finishing the steel billet two ends reinforcement heating that soaking is about to come out of the stove, the furnace temperature of strengthening heating region is higher than 80～120 ℃ of soaking zone furnace temperature, 20～30 seconds heat time heating times.

2, in soaking zone end, set up a local strengthening heating clamber 7, the both walls of local strengthening heating clamber or furnace roof both sides according to the steel billet kind, are equipped with 1 pair of burning at least and chew 5 pairs and finished the steel billet two ends that soaking is about to come out of the stove and strengthen heating.The burning of local strengthening heating clamber is chewed and is placed in both walls or arc inner concavity place, half garden, furnace roof both sides, installs that 1 pair of burning is chewed when square billet (heating), 2～3 pairs of burnings are chewed (during the heating slab), as Fig. 7, shown in Figure 8.The furnace temperature of strengthening the heating clamber both sides is higher than 80～120 ℃ of soaking zone furnace temperature, 18～30 seconds of heat time heating time.It is to form even heat radiation that the advantage of chewing is burnt in the installation of arc inner concavity place, above-described half garden.

Claims (2)

1, local strengthening heater before a kind of hot rolling steel billet is come out of the stove, it is characterized in that, the local strengthening thermal treatment zone of setting up at heating furnace soaking zone (3) end (4) or set up local strengthening heating clamber (6) is equipped with 1 pair of burning at least in the local strengthening thermal treatment zone (4) or local strengthening heating clamber (7) both walls or furnace roof both sides and chews (5).

2, local strengthening heater before hot rolling steel billet according to claim 1 is come out of the stove, it is characterized in that, described be equipped with to burn chew the local strengthening thermal treatment zone (4) of (5) or the side wall (6) of local strengthening heating clamber (7) both walls or furnace roof both sides is half garden arc inner concavity.

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