JPH06104267B2 - Continuous casting method and device - Google Patents

Abstract

1. Method for continuous casting in a continuous-casting mould having a mould cap (22) whose inner wall, while forming an overhang (8), protrudes beyond the inner wall of the continuous-casting mould, in which method the inner wall of the continuous-casting mould is cooled and lubricated, a gas under pressure, such as air, nitrogen or inert gas being fed at the overhang (8) of the mould cap (22) together with lubricant into the shaped hollow space into the continuous-casting mould, and a dummy block being used during casting, characterized in that a vacuum is produced in the gap between dummy block and mould running surface (7), and in that the parting compound and/or lubricant and the gas, before entry into the shaped hollow space of the continuous-casting mould (1), is mixed in a volumetric ration of 1-4:1000 while forming a gas/oil mist, and this mixture, starting at the overhang of the mould cap (22), is blown out in the discharge direction parallel to and along the mould running surface (7), a laminar flow being maintained.

Description

Description: INDUSTRIAL APPLICABILITY The present invention provides continuous casting in a continuous casting mold that has a mounting member whose inner wall projects from the inner wall of the continuous casting mold under the formation of an overhang. For cooling the inner wall of the casting mold and applying a lubricant, for the continuous casting of a gas under pressure, such as air, nitrogen or an inert gas, at the transition from the mold mounting member into the cavity. A method for introducing into a mold and a device for carrying out the method.

PRIOR ART A method and a device of the above-mentioned type are known from DE-A-2734388 [Skowa]. This known method only produces a somewhat smooth ingot surface under favorable preconditions.

During casting, for example, gas pressure and lubricant-flow rate monitoring and control, as well as continuous temperature measurements are required to adjust casting parameters. This is
It often presents difficulties in operation and is still strengthened in continuous casting processes by variations in metal liquid height and changes in metal static pressure.

Furthermore, it has been found that the method according to DE-A-2734388 does not satisfactorily cast lead-containing alloys having a lead content of up to 2.5%. However, this alloy is of particular importance for the production of continuously cast products to be machined.

Problems to be Solved by the Invention The object of the present invention is to avoid the above-mentioned drawbacks, and to develop a continuous casting method and apparatus capable of obtaining a smooth and clean ingot surface regardless of the respective casting conditions. is there. The special surface quality is superior due to the blocking of sticking points and the reduction of surface elution to the extent that post-treatment allows without turning the ingot.

SUMMARY OF THE INVENTION According to the invention, this problem is addressed by the features of the features of claim 1, namely mold release agent and / or lubricant and gas, the cavities of continuous casting moulds. Before inflowing, the mixture is mixed in a volume ratio of 1-4: 1000, and the mixture is ejected starting from the projecting portion of the mold mounting member in the drawing direction, parallel to the mold running surface and along the same. Will be solved. Controlling the casting parameters, in particular the gas and lubricant contents, by arranging the annular gap in the direction of the mold running surface and premixing the release agent and / or the lubricant and the gas, is carried out when the metal liquid height varies. But it turned out to be unnecessary. Experiments with gaseous lubricants such as acetylene, butadiene, propane and trichloroethylene show that under the conditions (pressure and temperature) prevailing in the mold, a satisfactory release action is not possible due to the decomposition of the gaseous lubricant. It was shown that. If the conventional lubricant is fed without gas parallel to the mold axis, combustion of the lubricant will occur during the start-up phase, followed by a shortage of feed. Therefore, in order to obtain the optimum lubricant state, it is impossible to supply the lubricant alone.

In the process according to the invention, it has been found important that the mold running surface below the overhang is absolutely smooth and free of perforations, steps or grooves. Especially during casting, the laminar flow must be kept parallel to the mold running surface in order to prevent the inflowing metal from coming into contact with the mold wall. This effect becomes remarkable by providing a minimum distance of 2 to 5 mm between the dummy bar and the mold running surface, and low pressure is generated in this gap especially by the cold water (water pump effect) ejected at the mold outlet end. It is strengthened by making.

Next, the present invention will be described in detail with reference to examples.

Example FIG. 1 shows a cross section of a mold according to the invention. A mold with a mounting member consisting of a hot head 2 and a gas guide block 3 with a gas passage 13 is recognized.
Perforations 4 for mold release agent and / or lubricant in the mold 1
And a water cooling passage 5 is included. An annular gap 6 is formed between the mold 1, the hot head 2 and the gas guide block 3, the annular gap 6 extending parallel to the running surface 7 and continuing to the running surface 7 at least in the vicinity of the outlet hole. . In this case, it is important that there are no projections, perforations or grooves at the running surface and at the exit of the annular passage, in order to allow a substantially laminar flow of the mixture of release agent and / or lubricant and gas. Is.

When operating, gas is blown through the annular passage 6 into the space below the overhanging portion 8 into the meniscus-shaped cavity 9. At that time, the gas entrains a part of the liquid mold release or lubricant, for example oil, at the lubricant supply point (perforations 4). gas/
An oil-mist (emulsion) is formed, which flows out in a laminar flow below the overhanging part 8 in the drawing direction and parallel to the mold running surface and between the mold 1 and the dummy bar. Reach into the gap. The effective low pressure created here by the water flow exiting the passage 5 allows for the formation of an annular gas / oil-mist which completely shields the mold wall 7 against liquid metal.

In a number of experiments it has been found that the gas / oil-mixture feed according to the invention does not have to be controlled by varying the pump pressure or feed even when the metal liquid height varies. It is clear that if a combination of gas / oil-mist and suction action along the running surface is applied, the buffer action between the metal and the running surface is always maintained even when the static metal pressure changes. Is.

The method according to the invention applies particularly to alloys which are susceptible to cracking. The following is an example of a strand having a diameter of 25.4 cm (10 inches) with a release agent to gas ratio of 3:10.
It was 00.

AlMg5 Casting speed 70mm / min AlCuMg2 Casting speed 65mm / min AlZnMgCu1.5 Casting speed 65mm / min AlCuMgPb Casting speed 65mm / min These casting speeds could be kept constant immediately after starting. Other casting parameters could not be adjusted. The obtained ingot surface showed high surface characteristics.

2 to 5 show another embodiment of the present invention. Compared with FIG. 1, the mold mounting member 22 in FIG. 2 is integrally formed. The perforations for the gas passages 14 are the mold mounting members 22
It exists inside and opens into a large front chamber 15 between the overhanging portion 8 and the mold running surface 7. Here, the mixture with the release agent and / or the lubricant flowing out from the perforations 4 in the mold 1 is formed. Water 11 to cool the strands 10
Is spouted from the passage 5.

FIG. 3 shows another embodiment of the device according to the invention. Here, the mold mounting member is horizontally divided into two parts 22a and 22b. The gas pipe 16 extends in the upper part 22a in the strand unloading direction and is blocked only by the gas distribution chamber 22c. The mold 1 has a support wall 12 for positively positioning the mold mounting members 22a, b. Other parts, such as the lubricant bore 4 and the gap 9, correspond to the structure according to FIG.

In FIG. 4, between the mold 1 and the hot head 2 another gas guide block in the form of an insert 17 is provided. In FIG. 5, the insert 18 is arranged between the mold 1 and the hot head in a corresponding manner. In the case of FIG. 5, unlike in FIG. 4, the gas passage 19 runs horizontally through the mold 1 and the insert member 18 into the front chamber 20, and the gas from the front chamber 20 into the annular gap 6. Reach The mixing with the lubricant supplied by the perforations 4 takes place variably between 2 and 10 mm in front of the exit hole of the annular gap opening. All other symbols correspond to the parts described in connection with the preceding figures.

[Brief description of drawings]

The accompanying drawings show an embodiment of the device according to the invention, FIG. 1 is a sectional view of the device according to the first embodiment, FIG. 2 is a sectional view of the device according to the second embodiment, 3 is a sectional view of the device according to the third embodiment, FIG. 4 is a sectional view of the device according to the fourth embodiment, and FIG. 5 is a sectional view of the device according to the fifth embodiment. 1 ... Mold, 2 ... High heat head, 3 ... Gas guide block, 4 ... Perforation, 5 ... Passage, 6 ... Annular gap, 7 ...
Mold running surface, 8 ... Overhanging part, 9 ... Meniscus-shaped void, 10 ... Strand, 11 ... Water, 12 ... Support wall, 13 ...
… Gas passage, 14 …… Gas passage, 15 …… Front chamber, 16 …… Gas passage, 17 …… Insert member, 18 …… Insert member, 19 …… Gas passage, 20 …… Front chamber, 21 …… Annular Gap opening, 22a, b …… Mold mounting part, 22c …… Gas distribution chamber.

Claims (9)

[Claims] 1. An inner wall of a continuous casting mold is cooled for continuous casting in a continuous casting mold having a mold attachment member, the inner wall of which projects from the inner wall of the continuous casting mold under the formation of an overhang, and In a continuous casting method in which a lubricant is applied, in which case a gas under pressure such as air, nitrogen or an inert gas is introduced into the continuous casting mold at the transition from the mold mounting member to the mold cavity. , Release agent and / or lubricant and gas are mixed at a volume ratio of 1-4: 1000 before flowing out into the cavity of the continuous casting mold, and this mixture is drawn from the overhanging part of the mold mounting member in the drawing direction. In addition, the continuous casting method is characterized in that jetting is performed in parallel with and along the mold running surface. 2. A method according to claim 1, wherein a low pressure is created in the gap between the dummy bar and the mold running surface. 3. A method as claimed in claim 1 or 2, wherein the casting and continuous casting are carried out with a constant amount of release agent and / or lubricant and gas. 4. A continuous casting mold having a mold mounting member, the inner wall of which protrudes from the inner wall of the continuous casting mold while forming an overhang, and the inner wall of the continuous casting mold is cooled and coated with a lubricant. In order to carry out a continuous casting method in which a gas under pressure, such as air, nitrogen or an inert gas, is introduced into the continuous casting mold at the transition part from the mold mounting member to the mold cavity. In the apparatus, a passage-like through-hole extending from a meniscus-shaped cavity (9) in a mounting member (22) existing on a mold (1) in parallel with and extending along a drawing direction of a strand. The continuous casting apparatus is characterized in that. 5. A continuous casting mold, wherein the inner wall has a mold attachment member protruding from the inner wall of the continuous casting mold under the formation of an overhanging portion, the inner wall of the continuous casting mold is cooled, and a lubricant is applied. However, in that case, air, a gas under pressure such as nitrogen or an inert gas, in an apparatus for performing a continuous casting method of introducing into the continuous casting mold at the transition portion from the mold mounting member into the mold cavity, An annular gap (6) is arranged in the overhanging part of the mold mounting member (22), the wall of which is adjusted mainly within the range of the outlet hole, parallel to the drawing direction and along the mold running surface (7). The continuous casting device is characterized by 6. A device according to claim 5, wherein the opening of the annular gap (6) is guided to the outlet hole parallel to the mold axis by 10 to 30 mm. 7. The mold release agent and / or the lubricant and the gas are merged within a range of 2 to 10 mm in front of the exit hole of the annular gap opening (21). The apparatus according to claim 1. 8. Mold running surface (7) behind the overhang (8).
8. The device according to claim 7, wherein the device is smooth and closed on each side. 9. A method according to claim 5, characterized in that there is a clearance of 2-5 mm between the mold running surface (7) and the starting block, and the dummy bar has an elevated edge surrounding the upper edge. The device according to any one of items 1 to 8.