EP1245310B1 - Continuous-casting mould with a hot top - Google Patents

Abstract

The ingot mold, for a continuous casting assembly, has a hot head (1) on the upper side of a barrier distributor (2), held and centered by an outer ring (4) in a release mounting at the ingot mold (3). The mold is surrounded by a metal or ceramic function ring (5), to the mold running surface, forming function surfaces with adjustable roughness together with the barrier distributor. The barrier distributor has radial channels at the upper and lower sides, with channel cross sections in a ratio of 1:3 to 1:5 between the upper and lower sides.

Description

The invention relates to a Heißkopfkokille for a Continuous casting plant consisting of a hot head on the Top of a release agent distributor rests and this with its underside against the surface of a mold presses, wherein at the radially inner surface of the Hot head, an overhang is formed, which over the Release agent distributor protrudes in the strand withdrawal direction and forms an annular gap with the Kokillenlauffläche.

A Heißkopfkokille of the type mentioned is out EP 0 566 865 (VAW), on the Release agent distributor passes release agent to the surface the cast strand, with two different release agents separately or as a release agent mixture of, for example fed to liquid separating oil and gaseous separation medium can be. It has already been recognized that it is special is favorable, if the oil-gas mixture only in the range of Mold is formed.

However, there are still problems regarding the Castability of so-called difficult to cast alloys, because here the surface quality is often insufficient. This is especially true for the lead, zinc, tin and Copper-containing aluminum alloys too. These have in Recently increased in importance for the production of special alloys and free-cutting alloys used in high cutting speed to be used.

In JP 56136257 is to improve the Surface quality proposed, the mold inner wall with To equip grooves in the casting direction. The grooves can also be arranged on an inserted functional ring.

Another problem is the exact control of the Gas pressure, which is crucial for whether the Release agent the entire surface of the metal strand reached. With pressure fluctuations it can be easy too Surface defects come and is at too high pressure the danger that gas escapes over the liquid metal.

To solve this problem is described in the US Patent 4,732,209 (Pechiney) proposed a graphite ring to use the Kokilleninnenseite whose porosity so is set that a pressurized gas from outside through the open pores of the graphite material up to the inside of the mold is pressed and there as Release agent between the surface of the resulting metal Stranges and Kokillenlauffläche acts. After our Experiences can not hereby be the problems with the Manufacture of malleable alloys are solved.

a) der Heißkopf 1 von einem Außenring 4 gehalten wird, der an der Kokille 3 lösbar befestigt ist,

b) dass die Kokille 3 zur Kokilleninnenfläche hin einen Funktionsring 5 umschließt, der zum Trennmittelverteiler 2 und zur Kokillenlauffläche hin Funktionsflächen mit definierten Rauhigkeiten bildet,

c) und dass der Trennmittelverteiler 2 aus einer beidseitig mit Radialkanälen durchzogenen Platine besteht, wobei die Kanalquerschnitte zwischen Ober- und Unterseite sich verhalten wie 1:3 bis 1:5.

Object of the present invention is to develop a Heißkopfkokille of the type mentioned in such a way that different types of alloys, especially heavy-cast alloys can be produced with satisfactory surface quality. As a solution, it is proposed that:

a) the hot head 1 is held by an outer ring 4, which is releasably attached to the mold 3,

b) that the mold 3 encloses a function ring 5 towards the inner surface of the mold, which forms functional surfaces with defined roughness towards the release agent distributor 2 and towards the mold running surface,

c) and that the release agent distributor 2 consists of a circuit board traversed on both sides by radial passages, wherein the channel cross sections between top and bottom behave as 1: 3 to 1: 5.

According to feature a), the new Heißkopfkokille of several Built rings that easily disassemble and to assemble. This makes it possible different Release agent distributor and functional rings depending on the desired Change alloy type quickly.

According to feature b), the invention is in the application a functional ring 5 with functional surfaces for Release agent distributor and the Kokillenlauffläche out. The Functional surfaces form wall sides with defined Roughness for the molded by the release agent distributor Channels, whereby it is particularly favorable here, if the Functional surface one wall side for the liquid-carrying Channel cross section forms. It has been shown that with a precisely adjusted surface roughness and Temperature of the functional surfaces a defined Viscosity change of the liquid release agent for production a stable foam layer can be achieved.

According to feature c) occurs in the release agent distributor the ratio of the channel cross sections to control the Composition of the release agent mixture on. By Combination of features b) and c) can cause foaming can be achieved, as a highly viscous release agent especially is effective and especially for difficult to cast alloys a very good surface quality allows.

According to claim 5 is proposed above the hot head 1 to arrange a clamping ring 6, with which the hot head 1, the Release agent distributor 2 and the mold 3 are braced can. After loosening the clamping ring 6 and the outer ring. 4 can the Tennmittelverteiler 2 and functional ring. 5 easily replaced. This is an adaptation of responsible for foaming surface and Channel cross sections easily possible.

According to claim 6, it is advantageous if for the Function ring 5 a defined, closed porosity and a specific density within narrow limits is selected. Additional improvements in stability of the release agent foam could by further experiments be achieved, wherein a cooling of the functional ring. 5 was made to increase the viscosity characteristics of the Keep functional areas constant. Construction and Function of the functional surfaces and the cooling is in explained in more detail in the following embodiments.

As already shown above, the Release agent distributor 2 on the top is preferred for the Formation of gas-carrying channels and on the bottom used for a liquid release agent The channels need to be made with very high precision, which for example by laser processing or by a chemical etching is achievable.

According to claim 8, it comes for the proportion of air in Release agent foam also on the cross-sectional shape of Radial channels of the release agent distributor and on the Area ratio of the channels to form a evenly distributed over the circumference release agent foam at. Under these conditions, the release agent particularly fine-celled and thus viable, so that the liquid component of the release agent is reduced can be.

The already mentioned cooling of the functional ring 5 takes place according to claim 9 preferably characterized in that in the mold. 3 Cooling channels are arranged, which extend into the area of the Functional ring range. In this primary cooling zone is a temperature for the optimum effect of the release agent set. In the subsequent secondary cooling zone is for a quick heat dissipation, since the cooling channels run here in strand withdrawal direction and in a Open slot nozzle. Here is the pressure of the coolant degraded, so that the cooling medium to the Aluminum strand applies and this cools down.

Figur 1

Gesamtansicht einer erfindungsgemäßen Heißkopfkokille in Explosions-Darstellung

Figur 2

Darstellung der erfindungsgemäßen Heißkopfkokille beim Stranggießen (Prinzipbild)

In the following the invention will be explained in more detail with reference to several embodiments. Show it:

FIG. 1

Overall view of a hot head mold according to the invention in an exploded view

FIG. 2

Representation of the hot head mold according to the invention during continuous casting (schematic diagram)

1

Heißkopf

2

Trennmittelverteiler

3

Kokille

4

Außenring

5

Funktionsring

6

Klemmring

7

Aktivatorring

8

Bodenteil

9

Druckblech

10

Metallstrang

11

Ringspalt

12

Trennmittelschaum

In the overall representation according to FIG. 1, the following system parts of the hot-head mold according to the invention are shown, which are joined together:

1

hot head

2

Release agent distributor

3

mold

4

outer ring

5

function ring

6

clamping ring

7

Aktivatorring

8th

the bottom part

9

pressure plate

10

metal strand

11

annular gap

12

Release agent foam

As can be seen from the claims training is certain functional surfaces of crucial importance for the formation of a stable separating agent foam. The Functional areas are located above and below the Release agent distributor and on the inside of the Function ring 5. This stands with the channels of the Release agent distributor 2 in direct contact and acts in the formation of the foam with.

As an innovation and addition of the functional surfaces will be a Aktivatorring 1 introduced, consisting of various Materials can be produced. The activator ring 7 lies between the outer ring 4 and the top of the Trennmittelverteilers 2. He covers so that in the Release agent distributor 2 incorporated channels towards the top from. Its roughness values are different from those of the hot head 1 and can adapt to the particular requirements of the Release agent can be adjusted. At the same time, so can the Heat transfer of lying below the hot head 1 Release agent distributor 2 are controlled.

A mold 3 is formed by an outer ring 4 and a Function ring 5 added. About a clamping ring 6 are the System parts including an activator ring 7 together. The mold 3 is completed by a Floor part 8 and pressure plate 9.

With reference to FIG 2, the basic structure of Hot head mold according to the invention further clarified and here especially on the neckline enlargement below the overhang of the hot head 1b are received. you detects an annular gap 11 below the overhang, where the side walls of the annular gap on the one hand by the Hot-head overhang and on the other hand by the inner radius of the release agent distributor 2 and by the functional ring 5 are formed. In the introduction of gaseous and liquid release agent within the invention Volume ratio is the formation of a stable Release agent foam 12, which turns out to be a closed Foam layer between the mold 3 and the strand 10th formed.

First, the surface roughness is the Viscosity of the release agent both in the gas and in the Fluid area controlled. The viscosity of the Release agent is the main factor in the Foaming. In addition, pressure and amount of controlled gas and liquid medium are controlled, so that the composition of the release agent foam within wide ranges is regulated.

With the release agent can turn a controlled Heat removal or made an insulating effect especially in the case of difficult to cast alloys of Advantage is.

Claims (11)

1. A hot-top mold for a strand casting apparatus comprising a hot top (1) lying on the top of the parting agent distributor (2) and pressing its bottom against the surface of the mold (3), an overhang being formed at the radially internal surface of the hot-top (1) protruding beyond the parting agent distributor (2) in the withdrawal direction of the strand and forming an annular gap (11) with the mold die-land surface,
   whereby
   the hot top mold is centered and held by an outer ring (4) releasably fastened to the mold (3),
   the mold (3) surrounds a function ring (5) in direction of the mold die-land surface which function ring (5) forms function surfaces in direction of the mold die-land surface with selected roughnesses, and radial ducts formed on the top and bottom surfaces of the parting agent distributor (2), whereas the ducts cross sections between the upper and bottom surfaces being in a ratio of 1:3 to 1:5.
2. The hot-top mold of claim 1, wherein the function ring (5) includes copper or copper alloys.
3. The hot-top mold of claim 1, wherein the function ring (5) includes ceramic or composite materials.
4. The hot-top mold of claim 1, wherein the function ring (5) includes graphite material.
5. The hot-top mold of claim 1, wherein a clamping ring (6) is disposed above the hot-top (1), by which the hot-top (1), the parting agent distributor (2), the function ring (5) and the mold (3) are clamped.
6. The hot-top mold of claim 5, wherein the function ring (5) has a closed porosity of 0 - 20% and a density of 1.5 - 10 g/cc.
7. The hot-top mold of claim 6, wherein the radial ducts, incorporated into the upper side of the parting agent distributor (2), are connected to a pressurized gaseous medium and that radial ducts are formed at the underside of the parting agent distributor (2) and are connected to a pressurized liquid reservoir.
8. The hot-top mold of claim 7, wherein the lower radial ducts of the parting agent distributor are configured in the manner of a diffuser, whereas an approximately square cross section being given to the radially outward lying passage carrying the parting agent distributor (2) and a rectangular cross section with a surface ratio of at least 1:2 being formed on the radially inward-lying exit side.
9. The hot-top mold of claim 8, wherein cooling ducts are disposed in the mold (3), which reach into the area underneath the parting agent distributor (2) and the function ring (5), heat removal being performed in the annular gap by a foam layer generated by the gas and liquid medium issuing in the descending direction of the strand.
10. The hot-top mold of claim 9, wherein the bottom part of the hot-top (1) has a thermal conductivity which is 1.5 to 2.0 times greater than that of the upper part of the hot-top (1).
11. The hot-top mold of claim 10, wherein the upper part (2) of the parting agent distributor (2) is covered by an activator ring (7).

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