CN104985163A - Device and method for improving product quality through interior ultra-cold nucleation of molten metal - Google Patents

Abstract

The invention provides a device and method for improving the interior quality of a casting blank through removing of the superheat degree of molten metal in the casting process and generating of a large number of free isometric crystal nucleation cores in the liquid phase to homogenize casting blank solidification. By means of the device and method, the superheat degree of the molten metal can be obviously reduced, and the ultra-cold degree is formed in part of the casting blank liquid phase so that a large number of isometric crystal nucleation cores can be generated; meanwhile, the multiple isometric crystal nucleation cores move into the liquid phase of the center of the casting blank in a vibration mode, a rotation mode and other modes to enable the interior of the casting blank to be rapidly and evenly cooled and improve the interior quality of the casting blank, and accordingly the requirement for the quality of special fracture surfaces (the interiors of large continuously-cast circular blanks and large casts), special steel grades (silicon steel, automobile plates and the like) and the like can be met. According to the device and method, repeated utilizing can be achieved, equipment cost and the using and maintaining cost are low, and the production cost cannot be increased basically while the interior quality of the casting blank is improved.

Description

The equipment improved the quality of products by the inner strong cold forming core of molten metal and method

Technical field

The present invention relates to the metal freezing such as continuous casting and die casting field, more specifically, relate to a kind of equipment and the method that are improved Inner Quality of Billet by the strong cold direct elimination molten metal degree of superheat in inside and generation equiax crystal forming core core.

Background technology

This sentences continuous casting is the explanation that example carries out technology and embodiment, but the present invention and method can be not limited only to casting process completely, is obviously applicable to the iron and steel such as continuous casting, die casting or other metal freezing fields.

In continuous casting production process, as shown in Figure 1, after molten steel passes through crystallizer 3 crystallisation by cooling from ladle 1 and tundish 2, form solidified shell, center is the strand 100 of molten steel and pulls out from crystallizer 3 end opening.Strand 100, after the pull-out of crystallizer end opening, carries out cooling twice, then after the aligning of pulling-straightening roller 4, arrives fire and cuts machine 5 by cutting front roller-way and carry out strand cutting.In above process, strand cools from outside to inside, can eliminate the degree of superheat of center liquid phase molten steel gradually, finally all solidify, define chill, dendrite and Center Equiaxial Crystal tissue, also because the reasons such as feeding finally cause center mass problem, i.e. shrinkage cavity, loose and segregation.

In order to improve the internal soundness of continuous casting billet, a lot of technological means is developed application, such as crystallizer electricity stirs, two cold electricity stir, end electricity stirs (M-EMS, S-EMS, F-EMS), such as slighter compress, heavy Reduction Technology, the such as strong refrigeration techniques of solidification end etc., these technological means can greatly improve and improve Inner Quality of Billet to a certain extent.But for special section, such as diameter is the large round billet of 600mm ~ 1200mm, Reduction Technology cannot be implemented, end electricity stirs and is proved invalid, and prior art means cannot change internal soundness substantially; For special steel grade, such as with the silicon steel etc. that slab is produced, require that strand has Center Equiaxial Crystal tissue as much as possible thus meets the isotropism requirement of product, current two cold roll-type electricity stir and can not reach requirement far away, and Reduction Technology does not act on substantially to increase strand equiaxial crystal ratio.

Another technique direction is that the mode by reducing the degree of superheat improves Inner Quality of Billet, and practice also proves, the degree of superheat reducing molten steel can significantly improve strand equiaxial crystal ratio and internal soundness.Therefore developed tundish electromagnetic induction heating and heating plasma technology, Prepared by Low Superheat Pouring and constant temperature cast can have been realized, be conducive to improving Inner Quality of Billet.But the enforcement of this technology will transform traditional tundish structure, at substantial electric energy, noise pollution environment on the one hand, the disposable input of another aspect, operation and maintenance cost are very high, and most steel mill does not afford to do; The third aspect, the Metal in Tundish degree of superheat can not ad infinitum reduce, and after lower than certain degree of superheat, easily causes tundish lower nozzle to wad a quilt with cotton stream, causes that single current is disconnected to be watered even casting machine and stop the accident of watering.

Summary of the invention

The present invention proposes to solve the above-mentioned problems in the prior art, it is a kind of brand-new technical thought, its object is to provide a kind of equipment and method, by eliminating the degree of superheat of molten steel in mold and producing equiax crystal forming core core raising Inner Quality of Billet, thus solve the production requirement of particulate metal section (the large round billet internal soundness of continuous casting, large scale foundry goods) and special kinds steel (silicon steel, Automobile Plate etc.).The present invention selects the degree of superheat directly reducing molten steel in the crystallizer of continuous casting or die casting process, overcome the risk that current technology causes tundish lower nozzle wadding stream, the requirement to the tundish degree of superheat can be loosened on the contrary, and effectively improve Inner Quality of Billet, be conducive to the Homogeneous cooling of strand and improve equiaxial crystal ratio, crystal grain thinning.

Described method is the present invention inserted in the molten metal of strand inside with the equipment of cooling, directly takes away liquid phase molten steel heat, the degree of superheat of the inner molten steel of strand is reduced greatly and even eliminates; Simultaneously under effect cold by force, stable solidification layer can be formed in the outside of cooling device, very large degree of supercooling can be there is in the outside of solidification layer, thus produce a large amount of forming core cores; Adopt the mode of the movements such as vibration or rotation, forming core core is impelled to dissociate in the liquid phase of strand inside continuously in large quantities, reduce in the strand internal liquid phase degree of superheat like this, under the acting in conjunction of local overcooling and a large amount of forming core core, impel strand inside to cool rapidly and uniformly.

Described equipment comprises cooling device and vibration unit, rotary unit, wherein form certain thickness molten steel solidification layer in order to guarantee in the outside of cooling device, cooling device requires to have higher thermal conductivity, cooling medium is chosen as water, material is the Heat Conduction Materials such as fine copper, cast copper, cast iron, cast steel, or different parts application unlike material.In order to ensure the stability of solidification layer, outside cooling duct, devise rib-groove or pattern structure; In order to form circulating cooling ability, cooling device includes inlet pipeline, inlet channel, water outlet and outlet pipeline.In addition, in order to ensure cooling uniformity, namely ensure the uniformity of water outlet water seam, cooling device devises positioner; In order to ensure that sealing avoids the accident caused of leaking, in the place that inlet channel system and water outlet system are connected and fixed, devise gasket seal.

Described equipment and method, also comprising the equipment and process parameter area designed to form enough intensities of cooling and a large amount of free forming core core, mainly containing: inlet channel diameter 20 ~ 50mm, water outlet water seam thickness 2 ~ 7mm, internal cold wall thickness 8 ~ 25mm, outer cold wall thickness 10 ~ 50mm, cooling device total length 50 ~ 1200mm; Cooling water flow velocity meets 3.0 ~ 15.0m/s, cooling device inserts the crystallizer molten steel surface degree of depth 5 ~ 1000mm; Vibratory equipment amplitude 0.1 ~ 4.0mm, shake frequently 30 ~ 1000HZ.

Described equipment and method, also comprise the security in order to use and meet the control system of technique adjustment, mainly contain: temperature measuring equipment, comprises and survey cooling wall local and turnover cooling water temperature; Intensity of cooling control software design; Vibration and rotation control software design.

Equipment provided by the invention and method, can reuse, and equipment self, operation and maintenance cost are all very cheap, while raising Inner Quality of Billet, substantially can not increase production cost.The scope of application of the present invention is at least continuous casting and die casting, can be applied to all metal freezing fields completely.Equipment provided by the invention and method, principle and functionally can substitute casting process Tundish Heating technology and two cold, end is electric stirs technology (S-EMS, F-EMS).

Accompanying drawing explanation

By reference to the content below in conjunction with the description of the drawings and claims, other object of the present invention and result will more be understood and should be readily appreciated that.In the accompanying drawings:

Fig. 1 is the schematic diagram according to conticaster of the present invention;

Fig. 2 is the schematic diagram according to present device;

Fig. 3 is the schematic diagram according to present device and embodiment of the method

Detailed description of the invention

In the following description, for purposes of illustration, in order to provide the complete understanding to one or more embodiment, many details have been set forth.But, clearly, also these embodiments can be realized when there is no these details.In other example, one or more embodiment for convenience of description, known structure and equipment illustrate in block form an.

Come below with reference to accompanying drawings to be described in detail each embodiment according to the present invention.

Fig. 1 is the schematic diagram according to conticaster of the present invention, method of the present invention can act in the region of crystallizer 3, heat is walked from strand inner band further by equipment of the present invention, eliminate the degree of superheat, producing dissociates to the forming core core in strand molten metal simultaneously in a large number accelerates and homogenising is solidified.

The present invention is by reducing the degree of superheat of molten metal and producing equipment and the method that equiax crystal forming core core improves Inner Quality of Billet, and Fig. 2 is the schematic diagram of present device.As shown in the figure, vibration/rotary unit 200 provides the relative movement of equipment and molten steel, internal cold wall 220 and outer cold wall 230 define cooling duct, comprise inlet channel 260 and water outlet water seam 250, in order to ensure that inlet channel and water outlet do not leak, there is gasket seal 210, simultaneously in order to ensure the precision that water outlet water stitches, devising positioner 240.

The flow direction of cooling medium is as shown by the arrows in Figure 2: enter inlet channel 260 from water inlet pipe 280, then water outlet water seam 250 is entered by the passage below internal cold wall 220, finally discharge from the upper end outlet pipe 270 of cooling device, like this, the amount of heat passed into outside outer cold wall 230 is constantly taken away by the flowing of cooling medium, external cold wall 230 cools on the one hand, ensure that it can not be melted, can reuse, take away amount of heat in molten metal on the other hand, reduce the degree of superheat, simultaneously form solidification layer and a large amount of equiax crystal forming core core outside cold wall 230 outside.These equiax crystal forming core cores, under the effect of vibration/rotary unit 200, by effects such as vibration and siphons, are left solidification layer, are dissociated in molten metal, become the forming core core consuming the molten metal degree of superheat and accelerated solidification further.

Obviously, the effect that reach, except the design of supercooling equipment, technological parameter is very important factor, the flow of such as cooling medium and flow velocity, and cooling medium flow velocity is too little, the deterioration of heat transfer can be caused and effective cooling cannot be reached, even can bring impact to the cooling device life-span; Such as vibration frequency and amplitude, too little to shake frequently and amplitude may be not enough to make forming core core depart from cooling device, and too large frequency and the amplitude of shaking may cause coming off of solidification layer.

Fig. 3 is the schematic diagram according to present device and embodiment of the method, the present embodiment acts in continuous casting steel billet production, the high-temperature liquid-phase molten steel with certain degree of superheat enters crystallizer 330 from the mouth of a river 310, under the cooling of crystallizer 330, define base shell 350, simultaneously because base shell cooling meat defines the air cleft 340 with crystallizer, along with constantly descending and cooling, base shell 350 meeting progressive additive, final strand departs from crystallizer 330, completes the cooling procedure in crystallizer.And at base shell internal high temperature molten steel 360, still there is certain degree of superheat, can't solidify very soon, simultaneously based on effects such as production, heat transfer and metallurgy, in crystallizer 330, molten steel 360 generally all can have covering slag 320 to cover above.

In embodiment as shown in Figure 3; by two equipment 1000 (including vibration unit 1100 and cooling device 1200) of the present invention; be arranged symmetrically with in the molten steel 360 of continuous casting steel billet tundish long nozzle 310 both sides; and be positioned at covering slag less than 320; it is cooled, simultaneously under vibration is auxiliary, forms a large amount of free equiax crystal forming core core; constantly enter in the molten steel 360 of strand inside, accelerate and homogenising molten steel 360 solidify.Obviously, the degree of depth of present device insertion covering slag less than 320 can produce material impact to embodiment effect.

According to another embodiment of the invention, act on continuous casting round bloom according to embodiment described in Fig. 3, can in the periphery 1 at the big round billet crystallizer mouth of a river, or be arranged symmetrically with 3,4 even more multiple stage present devices, thus the molten steel in large round billet strand is cooled, eliminate the degree of superheat, and produce a large amount of equiax crystal forming core core, entering in strand molten steel by vibrating to dissociate, accelerating and homogenising solidification of molten steel.Obviously, in the present embodiment, arrange that the quantity of present device can produce material impact to embodiment effect.

Although disclosed content shows exemplary embodiment of the present invention above, it should be noted that under the prerequisite not deviating from the scope of the invention that claim limits, can multiple change and amendment be carried out.The function of the claim to a method described in inventive embodiments described herein, step and or action need not perform with any particular order.In addition, although element of the present invention can describe or requirement with individual form, also it is contemplated that multiple, is odd number unless explicitly limited.

Claims (9)

1. the equipment improved the quality of products by the inner strong cold forming core of molten metal and method, being comprised:

Equipment with cooling is directly inserted in molten metal, eliminates the degree of superheat of the inner liquation of strand, produce local overcooling degree simultaneously;

Adopt mode cold by force, form stable solidification layer in the outside of equipment;

A large amount of forming core cores is produced in the outside of solidification layer;

Utilize vibration/rotation or the combination move mode of equipment self, impel forming core core to dissociate in the molten metal of strand inside in a large number continuously;

Under the acting in conjunction that the reduction of the strand internal liquid phase degree of superheat, local overcooling and a large amount of forming core core produce, impel strand inside to cool rapidly and uniformly, improve equiaxial crystal ratio, reduce segregation, crystal grain thinning.

2. equipment according to claim 1, comprising:

Cooling system;

Vibration unit;

Rotary unit.

3. cooling device according to claim 2, comprising:

Internal cold wall;

Outer cold wall;

Inlet channel;

Water outlet;

Water inlet pipe;

Outlet pipe;

Gasket seal;

Positioner;

Control system.

4. the material of cooling device according to claim 2, comprise the Heat Conduction Materials such as rolling fine copper, cast copper, cast iron, cast steel, and cooling device different parts adopts unlike material, material used determines cooling capacity, equipment life and safety requirements according to steel grade and process conditions, and processing technology is machining and casting.

5. the geometry of cooling device according to claim 2, comprise cross section for circular, oval and polygon etc., also comprising around the mouth of a river and cross section is toroidal; With tapering on length direction, and with local reducing process; Outer surface is light face or is provided with rib-structure such as groove, decorative pattern; Water outlet and water inlet position design at diverse location according to process conditions.

6. control system according to claim 3, comprising:

Temperature measuring equipment: the detection comprising the detection of cooling device own temperature and the Inlet and outlet water temperature difference;

Intensity of cooling control software design;

Vibration and rotation control software design.

7. the characteristic parameter of cooling device according to claim 2 and process parameters range are:

Inlet channel diameter: 20 ~ 50mm;

Water outlet water seam thickness: 2 ~ 7mm;

Internal cold wall thickness: 8 ~ 25mm;

Outer cold wall thickness: 10 ~ 50mm;

Cooling device total length: 50 ~ 1200mm;

Water flow velocity: 3m/s ~ 20m/s;

Insert steel level: 5 ~ 1000mm.

8. the characteristic parameter scope of vibration/rotary unit according to claim 2 is:

Amplitude: 0.1 ~ 4mm;

Shake frequently: 30 ~ 1000Hz;

Rotate: the reciprocal spin motion of low speed carrying out 1/2 or 1/4 circle etc.

9. equipment according to claim 1 and method, wherein, actual type of service also comprises: occur with monomeric form, or occur in combination.