FR2518913A1 - METHOD FOR SEMI-CONTINUOUS CASTING OF METALS - Google Patents

Abstract

THE INVENTION CONCERNS A SEMI-CONTINUOUS METAL CASTING PROCESS WITH PERIODIC ADMISSION OF THE LIQUID METAL 4 INTO THE LINGOTIER 1 FROM THE BOTTOM, UP TO THE PRIMING PLATE 2, THE STAY OF THE METAL IN THE LINGOTIER 1 SO AS TO FORM A SKIN 6 OF PRESCRIBED THICKNESS AND THE EXTRACTION OF THE HALF-PRODUCT OF LINGOTIER 1 FROM ONE EXTRACTION STEP, WITH SIMULTANEOUS INTRODUCTION INTO LINGOTIER 1 OF A VOLUME OF LIQUID METAL CORRESPONDING TO THE EXTRACTION STEP. FOLLOWING THE INVENTION AFTER THE INITIAL FILLING OF THE LINGOTIER 1 AND AFTER EACH FILLING FOLLOWING EACH EXTRACTION OF THE HALF-PRODUCT OF THE LINGOTIER 1 WITH ONE EXTRACTION STEP, THE INTRODUCTION OF THE LIQUID METAL 4 IS CONTINUED AND THE LINGOTIER 4 IS RIGGED UP TO - BEYOND THE LIMITS OF PRIMING PLATE 2, A VOLUME OF LIQUID METAL 4 BEING BETWEEN 0.1 AND 0.9 OF THE VOLUME OF THE USEFUL CAVITY OF LINGOTIER 1, AFTER WHAT, AT LEAST ONCE DURING THE LENGTH OF STAY, A PART OF THE said VOLUME OF LIQUID METAL 4 IS LOWERED IN THE HALF-PRODUCT IN FORMATION, THEN IT IS RAISED BEYOND THE LIMITS OF THE PRIMING PLATE 2, AND, DURING THE PERIOD OF COMPLETION OF THE TRAINING OF THE HALF- PRODUCT, THE MAIN PART OF THE VOLUME OF LIQUID METAL 4 IS RETURNED INTO THE HALF-PRODUCT IN FORMATION AND WE STOP MOVING THE LIQUID METAL 4 UNTIL THE COMPLETION OF THE SOLIDIFICATION OF THE HALF-PRODUCT.

Description

The present invention relates to methods of

  metals, and in particular, semi-batch casting processes

tinue metals.

  The invention can be applied in the field

  from the semi-continuous casting of metals, to the elaboration of

  semi-products with extraction from the top of the mold.

  In recent years, worldwide, the processes of continuous and semi-continuous casting of metals, which unlike casting in single molds or molds, have become increasingly integrated

  to reduce the production cycle of cast semi-finished products,

  lower labor costs, increase the return on

  to automate and mechanize the process and to

  to judge casting with rolling, which results in the ob-

  better products.

  There is known a method of continuous casting of half

  produced by successive solidification or successive freezing

  (see, for example, the work of V F Bevza and others, "The

  continued by successive freezing ", Moscow, Editions

  "Nauka i tekhnika", 1979, pp. 5-22 and 177-191), according to the

  which liquid metal is introduced by a casting system

  source in a mold to a seed tray.

  After formation of the skin of the half-product up to the thickness

  prescribed, we begin the periodic extraction of the half

  The mechanism of the liquid metal is then maintained at the same level (in the upper part of the mold or a little higher), and the metal is introduced into the mold in an amount equal to the volume of the skin.

  half-product extracted from the mold.

  However, in continuous casting by solidification

  successively, the creation of a surplus

  on the side of the liquid phase, on the skin of the half

  duit in the course of training) and we do not ensure the displacement

  of the liquid phase with respect to the skin being solidified.

  This is why, by this process, we can not

  semi-finished products of non-ferrous metal alloys having a large solidification range, since in this case the

  large extent of the solid-liquid zone in the section, pro-

  pre to these alloys, does not allow the formation of a half-pro

duit with homogeneous dense structure.

  There is known a method of manufacturing semi-pro

  in continuous metal casting plants (see, for example, the USSR inventor

  N 265385, class B 22 D 11/00, published 09 03 1970), comprising

  the periodic admission of liquid metal into ingots

  at the bottom to the seed plate, its stay in the mold to form a skin of prescribed thickness,

  extracting the semi-finished product from the mold with a step of

  traction with simultaneous admission into the mold of a quantity of liquid metal corresponding to the extraction step (quantity extracted) During the pause between the extractions of the semi-product of the mold, it is recommended to create an overpressure on the skin of the half -produced on the side of the liquid metal.

  However, in the known process, during the poor

  its between the extractions of the half-product of the mold there is no movement of the metal with respect to the front of

  solidification, which does not allow to sink half

  quality products for a series of alloys, for example

  aluminum and magnesium alloys, when the extrac-

  The half-product of the mold is periodic and when the liquid phase has a large extent (of a few meters)

  in the direction of the length of the semi-finished product For these alli-

  the casting of half-p Toduits, with a liquid phase of a length of a few meters and with a periodic extraction of the semi-product of the mold in the absence of a permanent movement of the metal with respect to the solidification front, causes the appearance, in the half-products section, of

  segregation bands that lower their quality.

  It has been proposed to create a casting process

  semi-continuous process of metals which would make it possible to

  formation of the skin of the semi-finished product, thanks to the

  implementation of new modes of action.

  The solution of this problem consists in a process of semi-continuous casting of metals, including the periodic introduction from below of the liquid metal into the mold.

  up to the priming plate, the stay of the metal in the lin-

  cup to form a skin of the prescribed thickness and

  extracting the semi-finished product from the mold with a step of

  traction with simultaneous introduction into the mold of a -

  volume of liquid metal corresponding to the extraction step, characterized in that, '' according to the invention, after the initial filling of the mold by the liquid metal and after each filling liquid metal following each

  extraction of the semi-finished product from the mold with a step of

  traction, the introduction of the liquid metal is continued and

  raises beyond the limits of the priming

  a lume of liquid metal lying between 0.1 and 0.9 of the volume of the useful cavity of the mold, after which, at least once during the residence time, a portion of said volume of liquid metal is lowered into the semi-finished product

  training course, then it goes back beyond the limits of

  mites of the seedbed, and before completing the training

  of the semi-finished product, the main part of said volume of liquid metal is returned to the semi-finished product and the liquid metal is stopped

  the completion of solidification of the semi-finished product.

  This makes it possible to increase the quality of the cast half-product both in its superficial layers and throughout its section.

  It is advantageous to carry out the initial introduction

  of the liquid metal in the ingot mold from below and from above, then, at the end of the residence

  from below the volume of liquid metal needed to fill it

  of the ingot mold during the extraction of the semi-finished product from a step, and to extract the semi-finished product from the mold by also introducing the liquid metal into the mold.

  ingotiere simultaneously from the top and the bottom.

  Such a filling regime of the ingot mold

  to improve the quality of the cast semi-finished product and

  the power of the devices (eg induction pumps) supplying the liquid metal mold.

  It is recommended, when rising metal

  beyond the limits of the priming plate, to increase the inlet pressure of the liquid metal in the mold

from 1.1 to 15.0 times.

  This gives the possibility to create during the break, on the solidified skin of the semi-finished product, inside the mold, an effective pressure increased from 2 to 3 x 10 Pa (2 to 3 atm) and m 9 more, which has a positive influence on

the quality of the cast half-product.

  It is desirable, when returning some of the liquid metal from the top, in the semi-finished product.

  training, to increase the pressure in the liquid metal

  sufficient value to overcome the pressure of introduction

  the production of liquid metal in the mold -

  Only such conditions make it possible to ensure the return of the prescribed quantity of liquid metal in the semi-product being formed without reducing the introduction pressure; It is advantageous, during the initial introduction of the liquid metal into the mold from below and from above, to achieve the introduction of the liquid metal from the top with a certain advance compared to its introduction.

from the bottom.

  This removes the initial spurt

  liquid metal introduced into the mold from below.

  It is recommended, when extracting the half

  of the ingot mold a step, to introduce the free metal

  quide in the mold with advance of the introduction by

  down on the introduction from above.

  Such a regime for introducing liquid metal into the mold makes it possible to exclude the inner surface of the skin of the semi-finished product being discovered during training

by the liquid metal.

  It is advantageous, after the cessation of

  liquid metal, to create an increased pressure

  in the liquid metal, at the top and at the

lower part of the semi-finished product.

  This gives the possibility of raising the quality of the

  heart of a solid half-product at the terminal stage of its

  tion. In the following, the invention is explained by a nonlimiting example of implementation, with reference to the accompanying drawings in which: Figure 1 shows the time of initial filling of the mold liquid metal;

  FIG. 2 is the distribution pattern of the pres-

  on the skin being formed, on the side of the metal

  quide, when filling the mold, following the

gure 1;

  FIG. 3 is the same outline as that of FIG.

  re 2, but when the mold is completely filled;

  Fig 4 shows the formation of the skin of the

  half-produced during the stay;

  FIG. 5 is the distribution pattern of the pres-

  when a portion of the liquid metal rises beyond the limits of the seed plate;

  FIG. 6 is the same outline as that of FIG.

  re 5, but when the liquid metal returns to the semi-pro-

duit during casting;

  FIG. 7 shows the moment of extraction of the half

product of the mold;

  FIG. 8 is the distribution pattern of the pres-

  during extraction of the semi-finished product from the mold; Fig 9 shows the formation of the half-product after the first extraction, during the stay;

  Fig. 10 is the distribution pattern of the pres-

  when a portion of the liquid metal rises beyond the limits of

  mites of the seed plate; Fig 11 is the purge of pressure distribution during the return of the liquid metal in the semi-product during casting; Fig. 12 shows the initial filling of the mold when the liquid metal is introduced from below and from above; Fig. 13 is the pressure distribution pattern when filling the mold according to Fig. 12; Fig. 14 shows the end of filling of the liquid metal mold;

the F Ig rs p ddi-stributiord -la-

  pressure at the end of the filling of the mold, according to FIG. 14; Fig. 16 shows the formation of the skin of the semi-finished product at the beginning of the residence time; Fig. 17 is the pressure distribution pattern at the beginning of the residence time, according to Fig. 16;

  Fig. 18 shows the formation of the skin of

  half-produced at the end of the length of stay; Fig. 19 is the pressure distribution pattern at the end of the residence time, according to Fig. 18; Fig. 20 shows the extraction moment of the mold of the skin formed from the semi-finished product; and Fig. 21 is the distribution pattern of the

  during the extraction of the semi-finished product from the

SPECT.

  The process which is the subject of the present invention

  This is described on the basis of an example of semi-con-

  tin of aluminum alloy semi-finished products, the metal

  which is introduced into the mold from below, by examination from a metal pneumatic distributor. Before starting the casting of the semi-finished product,

  performs the preparatory operations including: the bet.

  in place, on the upper part of the ingotigre 1 (FIG. 1), a priming tray 2 and its sealing; the connection to the boot tray 2 of a system 3 allows

  both to evacuate and to introduce liquid metal; and the replacement

  liquid metal pleating of pneumatic receiver-distributor

  tick (not shown in the figure) of metal from a mixer.

  Then, one preferably introduces into the receiver

  The liquid metal 4 is then discharged through a conduit and fills the mold 1 cooled with water. As the liquid metal fills the

  ingot mold 1 is formed on the active surface of the

1, a skin 6.

  The introduction of the liquid metal through the con-

  5 must ensure the complete filling of the mold 1 in 3 to 8 seconds, because a slower filling would be the cause of too great a time difference in the formation of the skin 6 in the lower part and the upper part

of the mold 1.

  The distribution (distribution) of the static pressure

  4 of the liquid metal 4 according to the height of the mold 1, shown in Figure 2, corresponds to the filling of the mold 1 of liquid metal 4 to the level shown in Figure 1 The pressure P 'is the inlet pressure and

  it corresponds to the pressure in the liquid metal 4 (FIG.

  re 1) at the inlet of the mold 1.

  As the ingot mold 1 is filled with the liquid metal 4, the intake pressure changes by

zero to P (see Figure 3).

  After complete filling of mold 1 (FIG.

  4) by the metal 4, the introduction of the free metal

  4 through the conduit 5, a certain volume of liquid metal 4 being discharged beyond the limits of the platen 2 priming

25189 13

by the system 3.

  Then, the liquid metal having been evacuated beyond

  Bootstrap 2 boundaries are returned to the lineup.

  and then evacuated beyond the limits of the

  2 priming water. It is recommended that the volume of liquid metal 4 discharged beyond the limits of the priming plate 2 is between 0.1 and 0.9 of the volume of the mold 1.

  liquid metal 4 discharged beyond the limits of the plateau 2 of

  Morching is determined primarily by the condition

  that it must be sufficient to ensure the required regime of

  on the layer of the semi-finished product being

  lification For blanks to cast small sections (100 to 200 mm), this volume can go up to 0.9 of the volume of the ingot 1 and for blanks to cast sections

  greater than 500 mm, the rational proportion is 0.1 to.

  0.2. Towards the end of the filling of the mold 1 by

  the liquid metal (Figure 4), it is established at the entrance of the

  In this case, an inlet pressure P 2 1.1 P1 (see FIG.

  Increase of the inlet pressure of the metal

  liquid 4 (FIG. 4) in the mold 1 of 1.1 times

  the rise of liquid metal beyond the limits of

  2 priming water, the pressure prevailing in the liquid phase

  the half-product being only the metallostatic pressure.

  During the rise of the liquid metal 4 beyond the limits of the priming plate 2, the resistance opposite to the flow of the liquid metal 4 evacuated is increased, which results in an increase in the inlet pressure of

  several times, for example 10 to 15 times.

  Said increase can be obtained by action

  overpressure, produced by external forces,

  example by a compressed gas, electromagnetic forces, etc. The increase of the inlet pressure of the liquid metal 4 in the mold 1 in a range-up to

  times, during breaks between extractions of half

  product of mold 1, allows to create on the skin so-

  of the semi-finished product, in the zone of the mold 1, an increased pressure of up to 2 or 3 × 10 5 Pa and more, which has a favorable effect on the quality of the half-product.

duit cast.

  If, for example, a semi-finished product is

  aluminum binding whose specific weight in the liquid state is 2.5 g / cm, in a mold 1 of a length of 1 m, it is necessary to mount the liquid metal 4 in the tray 2 priming placed on the top of the mold 1,

  that the effective pressure of admission is Pl = 0.25 x 10 Pa.

  To continue the introduction of liquid metal 4 so

  to evacuate a certain volume beyond the limits of the

  2 and during this time the pressure is

  the prescribed zone, for example 2.5 x 10 Pa in the zone of the mold at the bottom, it is necessary to increase

the intake pressure of 10 times.

  If, on the other hand, a magnet alloy

  sium-lithium whose specific weight in the liquid state is 1.6 g / cm, it is necessary, to raise it to a height of 1 m, an effective intake pressure of 0.16 x 10 Pa. continue the rise of the liquid metal 4 beyond the limits of the priming plate 2 and create at the lower part of the mold 1 the same effective pressure increased by 2.5 x Pa, the intake pressure must be increased by 15 time. The above clearly explains why it is recommended to increase the intake pressure from 1.1 to 15

time.

  In some cases it may be necessary to increase

  put the intake pressure more than 15 times, for example

  for the casting of a lighter metal, if 'the length of

  ingot mold 1 is less than 1 m and if the pressure

  Increased activity in the ingot mold area 1 is

less than 2 or 3 x 105 Pa.

  In this way, the formation of the skin of the half-pro-

  in the zone of the ingot mold 1 is carried out with the action of an increased pressure (up to 3 x 105 Pa eff) of the c 8 t of the liquid phase, as well as with a permanent movement of the liquid metal with respect to the solidification front of the half-product. Under such conditions, the semifinished product being formed is completely filled with liquid metal 4

  permanence and the movement is obtained by varying the volume

  me of liquid metal 4 exiting beyond the limits of the platen 2 priming, followed by the return of this liquid metal in the

ingot mold 1 -

  The displacement of the liquid metal 4 in one direction and

  in the other a predetermined number of times is

  during the rate of displacement of the liquid metal 4 inside the semi-finished product and the duration of the initial formation of the skin of the half-product before its extraction from

the mold 1.

  For this, after increasing the pressure of ad-

  mission the number of times prescribed, we create in the metal

  quide 4 an overpressure using external forces It

  the result is an increase in the pressure at the entrance to

  This pressure is maintained in the liquid metal 4 (FIG. 4) until all the volume or part of the volume of liquid metal 4 has been removed.

  evacuated beyond the limits of the priming tray 2 be

  led in pneumatic metal receiver-distributor.

  The need for an additional elevation of the

  pressure in the liquid metal 4 returning to the receiver-dis-

  metal pneumatic tribune from above, through the line

  taste 1, is explained by the fact that only such conditions

  allow the return of the prescribed quantity

  of liquid metal 4 without decreasing the pressure at the inlet

if we.

  Such a regime of formation of the skin 6 half

  produced in the ingot mold 1 improves the conditions of the

  solidification of the metal, which is particularly important

  both in the casting of complex aluminum alloys, having a wide range of solidification temperature and a large extent of the solid-liquid zone in the section of the semi-product being formed. The pressure created improves the supply of liquid metal 4 of the current half-product

  solidification, and the movement of the liquid metal 4 decreases

  the extent of the solid-liquid zone in the section of the semi-finished product. Before extracting the semi-finished product from the mold 1, the pressure in the liquid metal 4 is lowered, preferably to the value P 2 (FIG. 5), and then the semi-finished product of the mold 1 is rapidly extracted. (see Figure 7), an extraction step i, then increasing the inlet pressure P 2 to P 4 (see Figure 8) proportionally to

the value of the extraction.

  At the end of the extraction of the semi-finished product from

  gilt 1 (see Figure 9), we move up beyond

  the limits of the priming tray 2 the prescribed volume of

  4 and increase the inlet pressure of some

  by increasing the resistance to the flow of the liquid metal 4 evacuated, by creating a pressure equal to

P 5 (Figure 10).

  During the break between the extractions of the half

  of the ingot mold 1 (FIG. 9), the same

  mode of action than before: it is moved several times the prescribed volume of liquid metal 4 relative to the platen 2 priming in one direction and the other, the pressure created at the inlet of the mold 1 on return from

  liquid metal 4 having the value P 6 (see FIG. 11), larger

  that the intake pressure P 5 (see Figure 10).

  Then, with an inlet pressure not lower than

  than P 5, the following extraction of the half

  casting of the mold 1 (Figure 9); we perform an extrac-

  of a length equal to the extraction step, by introducing

  during the operation the necessary amount of free metal

  4 in the mold 1 and ensuring the increase

* necessary intake pressure.

  This done, the entire sequence of operations is re-

  until the semi-finished product is extracted from the

  prescribed. As mentioned above, filling

  ingot mold by the liquid metal must be

  kill as soon as possible (for example in 3 to 8 s) The skin

  formed of the semi-finished product must also be extracted from

  quickly and the introduction of the liquid metal into the mold in accordance with the extraction step must also be fast If said metal is discharged by an induction pump,

  for example for the casting of half-alloy products of

  gnesium, a high flow rate pump is required, requiring

  increased energy costs The speed of ex-

  traction of the semi-product of the mold, and thus reduce the energy expenditure, by employing a lower flow induction pump, but in this case, the thickness of the skin formed of the semi-finished product will be irregular along the length extraction step, which will lower the quality of the product

  The reduction of the extraction speed, when the

  the semi-product of the mold is drawn periodically,

  adversely affects the quality of the surface of the cast semi-finished product.

  To increase the filling speed of the line

  the following regime of introduction of the

liquid metal.

  After completion of the preparatory operations, the

  filling the ingot mold 1 (see FIG. 12) with liquid metal

  4 is made from below, via the duct 5, and, in addition, from above, via the system 3 connected to the priming plate 2 The gas is discharged from the mold 1 through

  an orifice of the priming plate 2, closed by a valve 7.

  The inlet pressure is then P1 (see FIG. 13).

  In this case, the rapid filling of the mold 1 (FIG. 12) by the liquid metal 4 does not require the use of a high-flow induction pump because, to fill the mold 1 with the liquid metal 4, the pump can only repress 1/4 to 1/2 of the required volume of liquid metal

  4, the rest can be introduced from the top, via the sys-

teme 3.

  During the initial filling of the mold L by

  the liquid metal 4, it is permissible to carry out the introduction

  metal production from the top with a certain advance

  eliminates the initial spouting of the metal admitted into the mold 1 from below The suppression of the spouting of the liquid metal 4 during the initial period of the filling of the mold 1 makes it possible to lower the saturation of the liquid metal 4 by the gas and to raise the quality of the half-product

by increasing its density.

  When the introduction of the liquid metal 4 from the top is ahead of the introduction from below, at the end of the filling period the liquid metal 4 (see FIG. 14) only arrives in the mold 1 by the bottom , with a

  intake pressure P1 (see FIG. 15).

  After complete filling of the mold 1 (see FIG. 16) with the liquid metal 4, the skin 6 of the semi-finished product begins to form on the active surface of the mold 1. The introduction of the liquid metal is then continued via the leads 5 and via the system 3 connected to the tray 2

  The system part 3 introduces the part of

  liquid 4 which will be admitted into the mold 1 from the top during the extraction of the skin 6 formed during

  the introduction of the liquid metal 4 by the system 3, the pressure

  sion created at the inlet of the mold 1 is P 2 (cf.

17).

  Since the duration of the break is greater than

  the extraction time from 3 to 20 times, an inductive pump

  relatively low flow rate can transmit

  the pause, from the bottom up, a sufficient quantity of

  from the metal receiver (not shown on the

  drawings) In the case of such a regime for the introduction of

25189-13 -

  liquid, the power of the pump can be lowered from 2 to 3 times and more o At the end of the introduction of the liquid metal 4 (see Figure 18) in the system 3, we put the induction pump to a regime blocking o the pressure developed by the pump

  induction in the liquid metal prevents its return, the de-

  placement of the liquid metal 4 ceases and can be created in the zone of the mold 1 an increased pressure determined by

the value P 3 (see Figure 19).

  Once the skin 6 (see FIG.

  for example 30 to 60 mm, formed in the mold 1, the pressure is lowered in the liquid metal 4,

  the inlet of the mold 1, up to the value P 4 (see FIG.

  re 21), and the skin 6 is rapidly extracted (cf. FIG. 20)

  of the ingot mold 1, with an extraction step i close to the length

  of the mold The liquid metal 4 is then introduced

  duit from the bottom and from the top, which ensures the filling

rapid ingot mold 1.

  The rapid filling of the mold 1 by the

  liquid metal 4, in the volume corresponding to step 1 of ex-

  traction of the skin 6 to the mold 1, allows a uniform beginning of the formation of the skin 6 of the half-product over the length

  of this step, with application of increased pressure on this skin 6 from the beginning of its formation, when it is still relatively thin The implementation of a

  such a mode of action improves the quality of the superficial

  of the semi-finished product and, in particular, increases the index

of plasticity.

  In casting, for example, magnesium alloys

  lithium by the method generally adopted, in semi-finished products, it appears defects in the form

  growths, inclusions of fluxes and cracks-su-

  perfected, resulting in a healthy metal yield

  is often between 40 and 50%.

  If the ingot with defects is not

  rejected, but sent to encrusting, for half

  magnesium-lithium alloy products with a diameter of, for example, 600 mm, it is necessary to remove a surface layer with a thickness of 30 to 50 mm This peeling

  by itself lowers the healthy metal yield by 20 to 30%.

  Obtaining the semi-finished product by the process

  the object of the present invention makes it possible to eliminate the

surface defects.

  During the extraction of the skin 6 (cf. FIG. 20) from the mold 1, with the introduction of the liquid metal 4 by the

  up and down, it is recommended to carry out the introduc-

  liquid metal 4 from the bottom in advance with respect to

  the introduction from the top This makes it possible to prevent the

  The meniscus of the liquid metal 4 is lower than the priming plate 2 and thereby exclude the inner surface of the skin 6 of the semi-finished product from being discovered by the patient.

  In this way, the said interstitial surface is protected

  against oxidation by oxygen that may be present,

  even if the gas admitted into the semi-finished product is an inert gas.

  At the end of the extraction of the skin 6 of a step

  2 D of extraction, we raise again, through the lingo

  1 and through the skin 6 extracted beyond the limits

  of the priming tray 2, the required amount of free metal

  quide 4, and the skin 6 of a new section of semi-finished product

is formed in the mold 1.

  Then, the operations of introduction of the free metal

  4 in the mold 1, forming the semi-finished product and extraction of the semi-finished product of the mold 1 are repeated until the half-product is extracted from the prescribed length. At the end of the extraction of the required length of semi-product from the mold, the formation of the semi-finished product with uninterrupted movement of the liquid metal is continued, until the prescribed wall thickness is obtained if

  it is a hollow half-product, after which the remains of

  liquid are poured into the receiver-distributor-tire-

  in the case of a semi-finished product with a solid section

  until the remaining unhardened section becomes

  not insignificant, for example, for a round half-product, until the remaining diameter reaches 30 to 60 mm, after

  which is returned to the pneumatic receiver-distributor

  almost all the liquid metal rising beyond the limits

  from the priming plate, the movement of the

  in the liquid phase during solidification, an increased stationary pressure is created at the upper part and at the lower part of the semi-finished product, which

  ensures its formation without appearance of axial porosity.

  The implementation of the process which is the subject of the

  The present invention therefore makes it possible to develop, in the installations

  semicontinuous semi-finished product casting

  good surface and structural qualities throughout the sector

  with complex alloys, eg aluminum

  or magnesium, a liquid phase of equal length to the lon-.

  half of the product to be cast being present in the half

  product in course of formation Compared to the generally adopted method of casting semi-finished products in complex alloys, the surface of the solidification front may be

  increased by several times (depending on the dimensions of the

  The duration of solidification of the semi-finished product can be reduced by about the same number of times, and, consequently, the yield of

  each line of the installation increases.

  The process makes it possible to cast semi-finished products in complex alloys without growths of liquor, which increases the yield of healthy metal and eliminates echo Qtage

subsequent semi-finished products.

189 13

Claims (5)

  1 Process for semi-continuous casting of metals,   taking periodic admission of a liquid metal (4) in   the mold (1) from below to a tray (2) of amor-   ge, the residence of the metal in the mold (1) so as to form a skin (6) of prescribed thickness and extraction of the semi-product of the mold (1) of an extraction step,   with simultaneous introduction into the ingot mold (1) of a   liquid metal lume (4) corresponding to the extraction step, characterized in that, after the initial filling of the   ingot mold (1) by the liquid metal (4) and after each   pleating of liquid metal (4) which follows each extraction of the semi-product of the mold (1) from an extraction step,   continues the introduction of the liquid metal (4) and   beyond the limits of the initiating plate (2) a volume of liquid metal (4) lying between 0.1 and 0.9 of the volume of the useful cavity of the mold (1), after which, at least once during the stay period, a portion of said volume of liquid metal (4) is lowered into the semifinished product during the formation, then it is moved upwards beyond   the limits of the seedbed (2) and, during the period of   of the formation of the semi-finished product, the main part of said volume of liquid metal (4) is   the half-product in the course of training and we stop   place the liquid metal (4) until the completion of the demification of the semi-finished product.   Process according to Claim 1, characterized in that the initial introduction of the liquid metal (4) into the mold (1) is carried out at the bottom and at the top and then, at the end of the residence time, from below the volume of liquid metal (4) necessary for filling the ingot mold (1) during the extraction of the semi-finished product from a   not, and the extraction of the semi-finished product from   (1) by also introducing the liquid metal (4) into   the mold (1) simultaneously from above and from below.   The process according to claim 1 or 2, wherein   in that, during the rise of the liquid metal (4)   beyond the limits of the plateau (2) of priming, the pressure   intake of the liquid metal (4) into the mold (1) from 1.1 to 15.0 times.   4. Process according to claim 1 or 2, characterized   in that, when returning some of the metal-li-   quide (4) from above in the semi-finished product being   tion, the pressure in the liquid metal (4) is increased   that sufficient value to overcome the pressure of admission   liquid metal (4) in the ingot mold (1).   Process according to claim 2, characterized in that, during the initial introduction of the liquid metal   (4) in the mold (1) from below and from above, the   troduction of the liquid metal (4) from the top takes place with a certain advance compared to its introduction from below. Process according to Claim 2, characterized   in that, during the extraction of the semi-finished product of the   (1) of one step, the metal-liquid (4) is introduced into the mold (1) with advance of the introduction from below. on the introduction from above.   The method of claim 1 or 2, wherein   characterized in that, after cessation of the displacement of the liquid metal (4), an increased stationary pressure is created in the liquid metal (4), at the bottom and at the bottom upper half-product. f