US3648763A - Machine for centrifugally casting tubular metal bodies - Google Patents

Abstract

Machine for centrifugally casting tubular metal bodies in a rotary mould rotating about an axis inclined at 1 to 10 percent. The machine includes a tubular pouring conduit having an inlet and an outlet for the molten metal and upwardly inclined from the inlet to the outlet at the same angle as the mould axis. Relative movement between the pouring conduit and mould causes the outlet to pour metal into the mould from one end to the other of the latter.

Description

nit ttes v atent Guenmi 1 Mar. 14 1972 [54] ACHHNE FlUR CENTRIFUGAILLY 1,351,767 9/1920 Ladd ..164/117 CAS'HNG TUBULAR METAL BOUHES 7,496 9/1923 Per y 164/117 X 3,162,909 12/1964 Sylvester... 164/337 X [72] Inventor: lEraldo Serahno Guenzi, Pont-A-Mousson, 3,297,436 9 7 Duwez 164/1 14 x France 3,299,480 1/1967 Woodburn et al.. ....249/l09 X 7 Assignee: Cenre de Recherches dc Pon1 A MouSson, 1,858,478 5/1932 Carnngton .164 17 Pont-A-Mousson, France I Primary ExammerR. Spencer Annear [22] Filed: Oct. 21, 1969 Attorney-J. Delattre-Seguy [21] Appl. No.: 868,671 [57] ABSTRACT Machine for centrifugally casting tubular metal bodies in a rokg 2 5 tary mould rotating about an axis inclined at l to 10 percent. [58] i 298 299 The machine includes a tubular pouring conduit having an 164/301 6 inlet and an outlet for the molten metal and upwardly inclined from the inlet to the outlet at the same angle as the mould axis. Relative movement between the pouring conduit and mould [56] References Cited causes the outlet to pour metal into the mould from one end to UNITED STATES PATENTS the other of the latter.

535,598 3/1895 Potter ..164/337 3 Claims, 7 Drawing Figures t o m Q91 l l 0 l .l c is MACEHINE EOE CENTEIIEUGAEEY CASTING TlUlBlUlLAlli METAL BODIES The present invention relates to machines for centrifugally casting metal tubular bodies in a tubular mould rotating about its axis. More particularly, the invention relates to the type of machines which comprise a channel supplying the mould with liquid metal and a device which produces a relative movement of translation between the channel and the mould so as to pour the liquid metal in an even manner from one end of the mould to the other.

The known machines of this type which are for'example, but not exclusively, applicable to the production of cast iron pipes have a liquid metal supply channel of the open type, that is, having a cross section roughly in the shape of a horseshoe. The liquid metal tlows by gravity, along this channel which is of great length and slightly inclined, its pouring end being slightly lower than its upstream end. The mould is roughly parallel to the supply channel. Theses machines include many improvements for improving the quality of the cast parts, for better controlling the amount of metal poured, for facilitating the maintenance or servicing of the pouring channel and for increasing the production rates.

In the research carried out by the applicant for achieving the foregoing improvements, a new method for centrifugally casting was discovered which satisfies these requirements and considerably simplifies the construction of the machine.

The object of the invention is to provide a method for centrifugaliy casting metal tubular bodies of the type in which the liquid metal is poured from one end to the other of the rotatable mould whose axis is roughly horizontal, wherein the liquid metal is injected under pressure in the form of a stream having a constant section and an adjustable flow.

Preferably, according to another important characteristic, the liquid metal is injected under pressure in a slightly ascending stream at a slope of between I and 10 percent and the pouring is stopped by stopping the pressure so as to stop the movement of this ascending stream of liquid metal, the metal being maintained liquid by heat insulation until the mould is once again available for receiving the pour of liquid metal, and the injection under pressure is resumed.

Another object of the invention is to provide a machine for centrifugally casting metal tubular bodies by means of the aforementioned method, said machine being of the type having a liquid metal container, a rotatable mould and a channel for pouring the liquid metal intended to penetrate the mould, the channel having an axis which is roughly parallel to that of the mould and a length exceeding that of the mould and being moved in translation relative to the mould for pouring the liquid metal in an even manner from one end of the mould to the other. In the machine according to the invention, the liquid metal container or pouring vessel is higher than a rigid rectilinear tubular conduit to which said vessel is connected, said conduit having a pouring orifice at its downstream end.

According to another feature of the invention, said conduit is slightly upwardly inclined in the direction from the end thereof connected to said vessel to the pouring end.

Owing to the invention, the conditions under which the liquid metal is supplied are more precise. Moreover, the construction and maintenance of the machine are considerably simplified.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. II is a diagrammatic assembly view of a machine according to the invention;

FIG. 2 is a detail view ofa tubular conduit partly cut away;

FIG. 3 is a detail sectional view showing the pouring of the metal inside the mould;

FIG. 4 is a diagrammatic view of a modification of the liquid metal supply device having a vessel pouring metal under pressure;

FIG. 5 is a diagrammatic assembly view, similar to FIG. 1, of a horizontal machine;

FIG. 6 is a detail cross-sectional view, to an enlarged scale, of the pouring spout or end of a tubular conduit for a horizontal machine, and

FIG. 7 is a diagrammatic view of a modification of the liquid metal supply vessel.

According to the embodiment shown in FIGS. l and 2, the invention is shown to be applied to a machine for centrifugally casting cast iron pipes in a tubular mould or shell A having an axis XX. The mould is mounted inside a carriage B which is movable in translation by a jack or piston and cylinder arrangement C. The mould A is driven in rotation by a motor D.

The metal mould A receives liquid metal which is for example supplied by a tiltable vessel E of known type.

According to the invention, the device supplying liquid metal to the machine is arranged as follows: a container t for the liquid metal, for example open in its upper part, is secured below the tiltable vessel E. In its lower part, the vessel E has a pouring nozzle 2 connected to the tubular conduit 3 of great length exceeding that of the mould or shell A. The container 1 into which the vessel E pours the metal is thus higher than the tubular conduit and therefore produces a pressure head.

This conduit, which is adapted to conduct liquid metal inside the mould A, is slightly upwardly inclined toward the carriage B, its downstream pouring end being higher than its upstream end connected to the container 1. The slope or inclination of the conduit 3 is between 1 and percent and preferably of the order of 3-4; percent.

Also according to the invention, the axis XX of the mould A is inclined the same degree and is parallel to the tubular conduit 3.

More particularly, the conduit 3 is composite and comprises (FIG. 2) in the following order from the interior to the exteria refractory tube 4 of great length which can be either in one piece or comprise elements which are assembled in end-to-end relation by sleeves or fitted inside each other;

- a heat-insulating refractory case 5 which is preferably flexible and for example comprises a felt of mineral wool sur rounding the tube 4 and held around the latter for example by means of spaced rings 6 of adhesive tape or adhered to the tube;

- an outer metal sheath 7, for example in two parts which are assembled in a diametral joint plane 8, this sheath terminates in a flange 9 for connection to the nozzle 2 of the container 1.

Note that the tube 4 is freely mounted inside the coaxial sheath 7 relative to which it is movable. This is permitted by the flexible refractory case 5. The tube 4, which open at both ends extends beyond the case 5 and the sheath 7 a certain length at its downstream end, namely the higher end (this extension is provided to preclude the stream of liquid metal from touching and harming the case 5 and the sheath 7).

The tubular conduit 3 is carried by with drawable supports MB of the type described in French Pat. No. 1,002.38). These supports are pivotable so as to allow the passage of the carriage B.

The centrifugal casting machine is completed by a mould stripping and extracting device for the cast tube F constituted by an extracting carriage (not shown) of known type which moves on the other side of the container 1 to the carriage B of the machine.

The machine operates in the following manner (FIG. I and 3):

With the mould A rotated at high speed, the container 1 is filled with liquid metal G up to an upper level N. As the container is higher than the conduit 3, the downstream end of this conduit 3 being at a. substantially lower level than the upper end of the container 1, the conduit 3 is completely filled with liquid metal which flows at a given pressure in the mould A. The carriage B moves toward the container 1, in the known manner, so that the mould A is supplied with metal from one end to the other. During the whole of the pour the conduit 3 remains full of metal G. This metal issues from the conduit 3 at an initial speed of V (HO. 3) which enables it to rise up to the slope of the mould A. Owing to the inclination x of the mould; the metal G is braked (FIG. 3) along a longitudinal distance a which enables it to be driven in rotation.

When the pouring end of the tubular conduit 3 reaches the other end of the mould A, that is, the lower end of the latter, the pouring is stopped by the fact that a level (N) of the metal G is reached in the container 1 which is equal to that of the upper end of the tubular conduit 3. The difference between the levels (N -N) correspond to the height required to afford the desired flow of metal.

During the solidification of the metal inside the mould A, its cooling and the extraction of the produced pipe F, the tubular conduit 3 remains completely filled with liquid metal which is at a sufficiently high temperature, at least during 2 or 3 minutes owing to the action of the refractory case 5,

As soon as the mould A is ready for a further casting after the tube F has been stripped from the mould it is merely necessary to once again fill the container 1 up to a certain upper level to restart the casting as mentioned hereinbefore.

Thus the procedure is to cast intermittently while maintaining the tubular conduit constantly full of liquid metal, even during the stoppages between pouring the duration of which are reduced to the minimum.

Note that the pouring is always carried out under pressure, but under a pressure which decreases as the level of the liquid metal in the container 1 drops, consequently, the metal flows as a rising liquid stream whose section is constant and corresponds to that of the tube 4 but whose flow decreases as the pressure drops. This pressure and flow remain known at each moment since the upper level of the liquid metal in the container l is known at the start of the pouring and the lower level upon stopping the pouring is known which corresponds to that of the downstream end of the tube 4.

Note, moreover, that the inner tube 4 and the outer sheath 7 of the tubular conduit 3 have substantially different expansions owing to the fact that their temperatures are very different (the inner tube 4 being at a temperature higher than l,O00 C. and the sheath 7 being at a temperature of the order of 400) and that the coefficients of expansion are very different, that of the steel sheath being much higher than that of the refractory tube 4. Owing to the freely movable mounting of the tube 4 inside the sheath 7 and to the flexibility of the heat-insulating case 5, the tube 4 and the sheath 7 are free to expand in a differential manner relative to each other irrespective of the temperature range. Note, furthermore that as the highest temperature corresponds to the lowest coefficient of expansion there is a certain compensation in the resulting expansion; that of the inner tube 4 cannot be different from that of the sheath 7.

The main advantages afforded by the invention are the following:

Owing to the tubular conduit 3, to the container 1 higher than the conduit 3 and to the rising slope of the tubular conduit 3, the stream of liquid metal has a constant section which corresponds to that of the tube 4. Since, moreover, the pressure of the pouring is constantly known by the level. i

As furthermore the pressure of the pouring is constantl known by the level of the metal in the container 1, the amount or flow of the liquid metal poured into the mould A is controlled with precision. Further, owing to these same characteristics and owing to the rising slope of the carriage B of the mould A, the flow of the metal into the mould is regular and calm because it is braked by rising slope of the mould. Consequently, a perfectly sound cast tube F is obtained. Further, the cast tubes all have the same weight within small tolerance since it is possible to control with precision the amount of metal poured into each mould by the supervision of the upper level of the start of the pouring and of the lower level at the end of the pouring in the container 1.

The flow out of contact with air in the conduit 3 avoids oxydation of the metal. The absence of a coating inside the tube 4 avoids the carrying along of coating products in the liquid metal and indesirable inclusions in the cast tube F.

Owing to the connection of the conduit 3 to the lower part of the container 1, the poured metal has no dirt and slag which are supernatant in the upper part of the container 1.

Owing to the constant filling of the tubular conduit 3 with metal remaining liquid, even during the stoppages of the pouring, many dead waste periods are eliminated relative to casting in known open horse-shoe sectioned channels since the tubular conduit requires no maintenance and no repairs between two successive pourings. The pouring interruptions are thus reduced to a minimum. This is advantageous not only as concerns the production rate, which is considerably increased, but also as concerns the temperature of the metal in the container l which is constantly renewed. In other words, the metal hardly has time to cool down in the container 1 during the pouring interruptions so that the metal is always poured at the highest possible temperature, which is beneficial for the quality of the parts cast in the mould A. r

As the metal always remains liquid in the heat-insulated conduit 3, only the amount of metal corresponding to the weight of a tube F is poured and losses of cooled and solidified metal in the supply channel are eliminated. Thus the saving in metal relative to the known method with an open horse-shoe sectioned channel can be considerable.

Lastly, the tubular conduit 3 is very simple in construction very cheap to make and requires no upkeep since it can be easily and cheaply replaced after a certain period of service.

The invention thus affords considerable advantages as to the construction and the operation of the centrifugal casting machine.

According to a modification shown in F IG. 4, the container 1 is replaced by a pouring ladle or vessel 11 operating under pressure having a spout 12 for receiving the liquid metal and a pouring spout 13. The latter is connected to the flange 9 of the tubular conduit 3. The pouring vessel 11 is hermetically closed in its upper part by a cover 14 through whichextends a conduit supplying fluid under pressure for example air or a neutral gas. This vessel of a well known type, constituting a tea-pot, is secured to a stand and supplies the tubular conduit 3 in perfectly sound metal since the slag'and the vslurries are supernatant in the upper part, as is the case with the container 1.

The pouring vessel 1] permits regulating the flow of the pouring the start of the pouring and the end of the pouring with even greater precision than before since it is sufficient to vary in a controlled manner the pressure of the fluid in the conduit 15 to cause the metal to rise in the tubular conduit 3 or, on the other hand, to maintain it stationary in this conduit, the pressure being then very low. It is easy to achieve constant a flow of the pouring by increasing the pressure of the fluid in the conduit 15 as the pouring ladle l l empties.

According to the embodiment shown in FIG. 5, instead of having a rising slope, the tubular conduit 3 and the carriage B and the mould A are perfectly horizontal. This has the advantage of facilitating the construction. But in this case, instead of the tubular conduit 3 being open at its pouring end, it has a bottom 16 and a pouring orifice 17 extending through the cylindrical wall of the tube near an upper generatrix in the neighborhood of this bottom 16 (see the cross-sectional view shown in FIG. 6). Preferably, the axis of the orifice 17 is inclined at an angle g relative to a horizontal diameter. This arrangement avoids that the tubular conduit become empty during a stoppage of the pouring. With the conduit 3 connected to, for example, a container, such as l, but if desired also to a pouring vessel employing pressure, such as 11, the liquid metal under pressure is projected upwardly inside the mould A in an oblique direction of angle 3 which enables it to drop back tangentially into the wall of the mould A. In this way, there is achieved a braking of the poured metal and its immediate driving in rotation when it reaches the wall of the mould A. As in the preceding case, the stoppage of the pouring of a container, such as l, is achieved when the level of the metal in the container 1 is at the height of the orifice l7 and if a pouring vessel, such as B11, is employed, when the pressure of the fluid in the conduit is suitably reduced.

Note that in order to completely empty the tubular conduit 3 at the end of a station it is possible to proceed either by direct emptying in the lower part of the container 1 or by tiltmg.

For emptying or draining, an orifice closed by for example a refractory plug is provided in the lower part of the container 1.

For tilting, instead of the container 1 or the pouring vessel 11 being mounted on a fixed stand, they are mounted on rollers which permit their tilting p. In this case the container and the pouring vessel preferably have the shape of a barrel having rolling rings carried by rollers whose axis are orthogonal to the tubular conduit 3 so as to allow the inclination of this conduit in a downwardly sloping manner so as to completely empty it by way of its downstream end. In the case of a pouring vessel employing pressure, the pressure of the fluid is reduced inside the pouring vessel and the conduit 3 can be inclined with a upward slope which is still greater so as to be emptied in the vessel.

Instead of the rolling rings mounted on rollers it is also possible to provide horizontal journals allowing the container 1 to tilt.

According to the modification shown in FIG. 7, the supply of liquid metal is achieved by means of a vertical tube 118 having a relatively great height H and connected to the flange 9 of the conduit 3 and surmounted by a shallow pouring vessel 19.

In this case, the variation in the level of the metal G in the vessel 19 on the course of pouring has little influence on the pressure and the flow, above all if the height H is great. The pressure remains practically constant and corresponds to the height H of liquid metal in the tube I8. Consequently, the pouring is effected with a constant flow.

Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims;

What we claim is:

ll. A machine for centrifugally casting tubular metal bodies, comprising a rotatable mound having an axis of rotation, a rigid tubular pouringconduit having an inlet adjacent one end of said conduit for receiving molten metal and a pouring outlet adjacent an opposite end of said conduit for pouring the molten metal inside the mould, said conduit having an upward inclination from said inlet to said outlet and said axis having the same inclination as said conduit inclination, said conduit and said mould being relatively movable between a position in which said outlet is within said mould and adjacent one end of said mould and a position in which said outlet is adjacent an opposite end of said mould, and means for causing said relative movement whereby molten metal can be poured from said one end to said opposite end of said mould.

2. A machine as claimed in claim I, wherein said inclinations are 1-10 percent.

3. A machine as claimed in claim 2, wherein said inclinations are between 3 and 6 percent.

Claims (3)

1. A machine for centrifugally casting tubular metal bodies, comprising a rotatable mould having an axis of rotation, a rigid tubular pouring conduit having an inlet adjacent one end of said conduit for receiving molten metal and a pouring outlet adjacent an opposite end of said conduit for pouring the molten metal inside the mould, said conduit having an upward inclination from said inlet to said outlet and said axis having the same inclination as said conduit inclination, said conduit and said mould being relatively movable between a position in which said outlet is within said mould and adjacent one end of said mould and a position in which said outlet is adjacent an opposite end of said mould, and means for causing said relative movement whereby molten metal can be poured from said one end to said opposite end of said mould.

2. A machine as claimed in claim 1, wherein said inclinations are 1- 10 percent.

3. A machine as claimed in claim 2, wherein said inclinations are between 3 and 6 percent.

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