EP0011650B1

EP0011650B1 - Flux powder supplying apparatus for continuous casting

Info

Publication number: EP0011650B1
Application number: EP19790900271
Authority: EP
Inventors: Shinji Nishida; Takashi Otsuka; Mitsukuni Sato; Satoru Kashimoto
Original assignee: Shinagawa Refractories Co Ltd
Current assignee: Shinagawa Refractories Co Ltd
Priority date: 1978-03-09
Filing date: 1979-10-09
Publication date: 1983-11-30
Also published as: JPS5724433Y2; EP0011650A1; EP0011650A4; JPS54133124U; DE2966437D1; WO1979000730A1

Abstract

Improvements in a powder feeding apparatus for continuous casting comprising a powder feeder (7) and a screw conveyor (11) carried by a truck (8) disposed in the vicinity of a casting mould, a guide rod (16) mounted on the screw conveyor (11), said guide rod being operatively associated with an arcuate guide (15) at the posterior portion of the screw conveyor (11), a crank mechanism (13) connected to the screw conveyor (11), a nozzle port (18) loosely fitted on the forward end of the screw conveyor (11) via the guide rod (16), and motors (12), (14) connected to the screw conveyor (11) and crank mechanism (13), respectively. This arrangement thus provides a powder feeding apparatus for continuous casting, wherein the nozzle port (18) can be adjustably reciprocated along the direction of the mold width. The optimum amount of powder can therefore be continuously charged uniformly spread over a molten steel surface during continuous casting.

Description

This invention relates to an improvement in a flux powder supplying apparatus for continuous casting, and more particularly to a flux powder supplying apparatus in which it is possible to charge and sprinkle an optimum amount of flux powder onto the surface of molten steel continuously and uniformly when pouring for continuous casting.
Generally, when molten steel is poured from a tundish to a mould in a continuous casting equipment, flux powder is sprinkled onto the surface of the molten steel in the mould, with the principal object of providing lubrication and heat retention of the molten steel.
Conventionally, flux powder is charged in such a way that the flux powder is placed above a mould, and the operator charges a suitable amount of flux powder while observing the surface of molten steel when pouring. However the working environment is deteriorated to a large extent because of the high temperature and powdery dust generated from the molten steel, with the result that the flux powder is supplied in an uneven distribution (i.e. uneven level).
There is presently known apparatus for supplying flux powder where a hopper or other container for the flux powder is remote from the mould. As is shown in U.S. Patent No. 3970135, French document FR-A-2336200 and Japanese Utility Model Publication No. 48581/76 a screw or other conveyor is used to transfer the flux powder to a position above the mould. However, these apparatuses have most important disadvantages in that it is difficult for a suitable amount of flux powder to be sprinkled uniformly onto the surface of the molten steel and that the conveyor is not capable of independent movement across the surface of the mould. Japanese Utility Model No. 48581/76 does provide for the hopper and conveyor to be driven together parallel to the width direction of the mould.
There is also known and used an apparatus (Japanese Utility Model Publication No. 39057/77) which uses a spring feeder, but it has less strength in view of its construction and thereby causes many troubles.
By the spring feeder is meant a feeder of known construction, in which a coiled spring is inserted, for almost all its length, in a flexible hose provided beneath a hopper containing flux powder. One end of said spring is directly connected to a motor, the flux powder proceeds following the rotation of said spring operating by means of the rotational, driving force of the motor, and then the flux powder is fed into said flexible hose to be supplied to a discharge port above a mould.
Further, Japanese Utility Model Publication No. 106410/77 proposes an automatic supply apparatus of flux powder, in which a supply pipe having an internally mounted screw is provided on the stand and the screw is driven by means of a motor fixed at the rear of said supply pipe. The nozzle opening at the end of the screw makes a back and forth arcuate movement in this apparatus, which is an improvement over what had gone before, still has the disadvantage that flux powder cannot be sprinkled linearly and uniformly.
In addition, because of the arcuate movement it is impossible to change or regulate the moving range (stroke) of the nozzle opening, as necessary, to the width direction of the mould, and it is impossible to exchange freely the nozzle opening for sprinkling flux powder in proper amount and evenly in conformity with the size of the mould.
Thus, conventional apparatuses having a spring feeder or a screw feeder have fundamental, constructional faults or operational inconvenience and demerits so that at present operational requirements are not satisfactorily achieved.
Since the scene of pouring operation is always under the circumstances of high temperature and flying duct, the constructional members become so fragile as to be unable to achieve the desired object, and it becomes impossible to control sufficiently the continuous, even feeding of flux powder in a proper amount.
According to the present invention, the disadvantages of the above-mentioned conventional apparatuses are eliminated, and the apparatus is simple but strong in construction and can perform accurate remote control. 1t is of strong construction in which a screw conveyor is provided swingably above the mould from the car, and to effect a linear, reciprocating movement of the nozzle opening at the end of said conveyor an arc-shaped guide and a crank mechanism are provided on the car off the mould. Furthermore the present apparatus can be easily, automatically operated.
The invention relates to a flux powder supplying apparatus for continuous casting of the sort which comprises a movable car arranged near a casting mould, a screw conveyor so mounted on said car through the lower portion of a flux powder supplying hopper as to be swingably movable in a substantially horizontal plane about a substantially vertical axis and a screw driving motor for said screw conveyor. Such an apparatus is known from Japanese Utility Model Publication No. 106410/77. The invention is characterised in that a crank mechanism is mounted on said car to impart a swinging motion to said screw conveyor, a guide rod is supported by a bracket member on said screw conveyor, one end of said guide rod being connected to a nozzle means defining a nozzle opening, said nozzle means being so mounted to the end of said screw conveyor as to be slidable in the longitudinal direction thereof, and the other end of said guide rod being held in an arc-shaped guide mounted to said car, the guide being so shaped and located that the nozzle means is reciprocally and linearly movable to charge and sprinkle an optimum of flux powder over the width direction of the mould.
The uniform sprinkling of flux powder in a suitable amount may be carried out by ensuring that the shape and dimension of said opening in the nozzle means slidably mounted at the end of the screw conveyor are exchangeable in response to the shape and kind of the mould. Thereby, nozzle openings of several shapes and dimensions may be prepared thereby enabling the possibility of freely mounting a nozzle opening with a desired shape and dimension.
Furthermore, the principal mechanism for the reciprocating linear motion of said nozzle is provided on the car and away from the mould, and therefore it is shielded from high temperature, powdery dust, the spray of molten steel, etc.
Accordingly, the present apparatus is very effective in view of safety and health, or strength and durability of the main portions of the apparatus, and further an accurate, quick remote control is possible by means of a separately mountable control board.
Thanks to a combination of said mechanism and members of the invention it is possible to sprinkle an optimum amount of flux powder continuously and at even thickness onto the surface of molten steel within the mould. Thus the invention provides a flux powder supplying apparatus for continuous casting, which is very useful in steel making or the like.
An embodiment of the invention will now be more particularly described with reference to the accompanying drawings, in which:

Fig. 1 is a vertical sectional view of one embodiment of the apparatus;
Fig. 2 is a plan view from above of Fig. 1;
Fig. 3 is a partially enlarged plan view showing a combination of screw conveyors and a guide mechanism;
Fig. 4 is a side view of Fig. 3;
Fig. 5 is a partially enlarged plan view showing a combination of two screw conveyors and a crank mechanism; and
Fig. 6 is a view to show a stroke regulation based on the relationship between a crank shaft and crank bolts, viewed from arrow a of Fig. 5.

Referring now to the drawings, molten steel 2 in a ladle 1 is received at a tundish 3, and the molten steel 2 is poured into a mould 5 through a tundish nozzle 4 mounted beneath the tundish 3. Flux powder 10 is uniformly supplied onto a surface 6 of the molten steel now poured, by means of a flux powder supplying apparatus 7.
In Fig. 2, WD means the width direction of the mould and TD the thickness direction of the mould.
The flux powder supplying apparatus 7 consists of a flux powder supplying hopper 9 placed on a movable car 8, a motor 12 for a screw beneath said hopper 9, and screw conveyors 11 connected directly to said motor 12. Flux powder 10 is fed within the screw conveyors 11, following the rotation of screw. The screw conveyors extend in a direction generally transverse to the width direction of the mould and are adapted to be swingably movable in a direction generally parallel to the width direction.
One end of a guide rod 16 extending above a screw conveyor 11 is slidably fitted into a guide 15 consisting of an arc-like groove, said guide being provided on the car 8 towards the rearmost end of said screw conveyor 11, and the other end of said guide rod 16 is mounted to the upper portion of a nozzle means defining a nozzle opening 18 slidably mounted at the end of the screw conveyor 11.
A bracket member 26 is fixed near the centre of the screw conveyor 11, the guide rod 16 is inserted slidably through said bracket member 26, by means of a bearing for example, and the nozzle means defining a nozzle opening 18 is supported by the guide rod 16 in such a way that it can move reciprocatingly and linearly in the width direction of the mould.
The guide 15 and the guide rod 16 engage with each other through sliding members 21 such as ball bearings.
The guide 15 is cut from a metallic material in the shape of an arc-shaped groove, the dimension and shape of which are so designed that it is possible for the nozzle opening 18 to carry out a reciprocal, linear movement. The guide rod 16 smoothly slides within said guide 15 and said sliding motion produces from the swinging movement of the screw conveyors 11 a reciprocating linear movement of the nozzle openings 18 slidably mounted at the ends of the screw conveyors 11.
The swinging motion of a screw conveyor 11 is effected by means of the crank mechanism 13 provided on the car 8, and a motor 14 is connected to said crank mechanism 13. The motor 14 is a motor with nonstep transmission capable of normal and reverse rotations for driving the crank mechanism.
By controlling the rotating speed of said motor 14 the rotating speed of the crank mechanism 13 can be optionally controlled, and as a result, it is possible to change freely the speed of the reciprocal, linear movement of said nozzle opening 18.
Further, as shown in Fig. 2 and Fig. 6, it is possible optionally to change and control the strike (the travelling distance) of the nozzle opening 18, to the width of the mould, by setting the crank bolts 20 at desired positions in a groove 22 bored at a crank shaft 23, and fastening said crank bolts 20 to fix them to the crank shaft 23.
As is clear from the drawings, a fulcrum 17 of the swinging motion is set correspondingly to the centre of the support stand of said flux powder supplying apparatus 7, at the rear portion of said screw conveyor 11.
A control board 19 is provided at a suitable position, said board being capable of controlling remotely the motors 12 for the screw conveyor and the motor 14 for the crank mechanism.
The above embodiment has been described with regard to a cast piece having a great ratio between the width and the thickness such as an ordinary slab, and therefore there are arranged in the drawings two sets of the flux powder supplying apparatuses 7 and screw conveyors 11. However, the number thereof is not necessarily limited to two, but depends on the size of the mould.
Fig. 3 and Fig. 4 show the guide mechanism, in which a guide rod 16 is inserted slidably above the screw conveyor 11, through a bracket member 26, and the upper portion of said nozzle opening 18 and the guide rod 16 are fixed at the end of said screw conveyor 11 whereby the nozzle opening 18 is slidable on the screw conveyor.
The other end of the guide rod 16 is inserted, to be slidable, into the guide 15 forming an arc-like groove, through sliding members 21 such as ball bearings, as shown in Fig. 3 for example, and the rearmost portion of the screw conveyor 11 is connected to a motor 12 thereby to rotate the screw while feeding the flux powder charged from the flux powder supply hopper 9.
Fig. 5 is an explanatory view of the construction of said crank mechanism 13 and said screw conveyors 11. Between two of the screw conveyors 11 (two or more can be arranged according to the operational conditions at the scene of casting) there are provided the crank mechanism 13 and the crank motor 14.
Said crank mechanism 13 is of the following construction. A crank rod 24 is connected through a pin 25 to a connecting member 27 fixed to the side face of the screw conveyor 11, and by means of crank bolt 20 the crank shafts 23 and the crank rod 24 are rotatably connected together.
Fig. 6 shows the crank shafts 23 only, viewed from an arrow a of Fig. 5, and it shows a mechanism capable of controlling, to optional and optimum set value, the stroke of said crank mechanism, in other words the stroke (the distance of reciprocating, linear motion) of the nozzle opening 18 slidably fitted at the end of the screw conveyor 11.
In order to set said stroke at the minimum stroke (MI) the crank bolt 20 is fixed at the position A as shown, in a groove 22 cut in the crank shaft 23, and if the setting to the maximum stroke (MX) is desired, the crank bolt 20 may be fixed at the position B, for example by means of nut.
The ranges of the maximum stroke (MX) and the minimum stroke (MI) are determined by setting the optional stroke between point A and point B by predetermining the length of the groove 22.
According to the invention, there are prepared in advance, freely exchangeable, several kinds of the nozzle openings 18 for which shape and dimension have been previously set, depending on the kind and size of the mould 5; by controlling the rotational speed of the screw motors 12 and the crank motor 14, it is possible to control the amount of flux powder supplied and the reciprocating linear motion stroke of the nozzle opening over a wide range; and it is possible to sprinkle a suitable amount of flux powder to the surface of molten steel in the mould, uniformly, efficiently, accurately and as desired.
Below is mentioned an example of numerical values of one embodiment (two screw conveyors) in the invention.
The major effects produced by the present invention are enumerated as follows:

(1) An optimum nozzle opening previously prepared is disengageably connected to the end of a screw conveyor so that the nozzle opening has great adaptability and exchangeability to various kinds of moulds.
(2) It is possible to supply and sprinkle flux powder into the mould sufficiently and uniformly in a proper amount.
(3) There are used no members which may become fragile at high temperature at all, and therefore the apparatus in its entirety is tough and can enjoy longevity, and accurate operation can be carried out whereby the apparatus has a great reliability.
(4) The supply amount and distribution range of flux powder can be regulated in a wide range, control can be made quickly and certainly, remote control can be effected smoothly, and the working places are hardly restricted because of the use of the car.
(5) The present apparatus is very effective in view of labour saving and environmental health.
(6) Since it is possible to control the flux powder supply most suitably for continuous casting operation, the defects of ingots produced can be decreased.

Claims

A flux powder supplying apparatus for continuous casting comprising a movable car (8) arranged near a casting mould (5), a screw conveyor (11) so mounted on said car through the lower portion of a flux powder supplying hopper (9) as to be swingably movable in a substantially horizontal plane about a substantially vertical axis and a screw driving motor (12) for said screw conveyor, characterised in that a crank mechanism (13) is mounted on said car to impart a swinging motion to said screw conveyor (11), a guide rod (16) is supported by a bracket member (26) on said screw conveyor, one end of said guide rod being connected to a nozzle means defining a nozzle opening (18), said nozzle means being so mounted to the end of said screw conveyor as to be slidable in the longitudinal direction thereof and the other end of said guide rod being held in an arc-shaped guide (15) mounted to said car, the guide being so shaped and located that the nozzle means (18) is reciprocally and linearly movable to charge and sprinkle an optimum amount of flux powder over the width direction of the mould.