US3756307A

US3756307A - Centrifugal casting machine with fluid pressure sealing means

Info

Publication number: US3756307A
Application number: US00268954A
Authority: US
Inventors: R Negre
Original assignee: Pont a Mousson SA
Current assignee: Pont a Mousson SA
Priority date: 1971-07-15
Filing date: 1972-07-05
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04
Also published as: DE2234678C3; FR2145419B1; FR2145419A1; CH555713A; ES405071A1; IT964652B; DE2234678A1; BR7204663D0; DE2234678B2

Abstract

Sealing means for a centrifugal casting machine. The sealing means comprise a flexible diaphragm having inner and outer peripheral portions fixed to the frame of the machine and a sealing ring secured to a first face of the diaphragm in a flexible portion the diaphragm intermediate the two peripheral portions and sealingly applied against a flange on a sleeve which defines an annular cooling liquid space around the mould. A part of said first face communicates with the annular space and a second face of the diaphragm opposed to the first face defines a chamber with a rigid wall fixed to the machine frame. The chamber communicates with a source of fluid under adjustable pressure.

Description

United States Patent 1191 Negre Sept. 4, 1973 [54] CENTRIFUGAL CASTING MACHINE WITH 3,272,572 9/1966 Lloyd 277/73 X Full" PRESSURE SEALING MEANS FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Robert Numa Paul Negre, Fumel, 1,176,227 1/1970 Great Britain 164/297 France Primary Examiner-Robert D. Baldwin 73 A :P t-- r l I sslgnee a Mousson S A Fumel Attorney-Richard C. Sughrue, Robert J. Seas, Jr.

et al. [22] Filed: July 5, 1972 211 Appl. No.: 268,954 [57] ABSTRACT Sealing means for a centrifugal casting machine. The sealing means comprise a flexible diaphragm having [30] Fore'gn Apphcafion Pnomy Data inner and outer peripheral portions fixed to the frame July 15, 1971 France 7125844 f the machine and a sealing ring secured to a first face of the diaphragm in a flexible portion the diaphragm [52] [1.8. CI. 164/297, 277/73 i t m diate the-two peripheral portions and sealingly [51] Int. Cl 322d 13/02 applied against a flange on a sleeve which defines an [58] Field of Search 164/297, 298; annular cooling liquid space around the mould. A part 72 of said first face communicates with the annular space and a second face of the diaphragm opposed to the first [56] Referenc C e face defines a chamber with a rigid wall fixed to the ma- UNITED STATES PATENTS chine frame. The chamber communicates with a source 3,589,435 6/1971 Mougin 164/297 fluid adjustable Pressure- 6 Claims, 3 Drawing Figures CENTRIFUGAL CASTING MACHINE WITH FLUID PRESSURE SEALING MEANS The present invention relates to machines for centrifugally casting metal pipes in a metal shell or mould cooled by immersion in a water jacket, and more particularly to sealing means for said water jacket formed between the shell, a rotary sleeve integral and coaxial with the mould, and fixed outer annular members integral with the fixed frame of the machine for supplying and discharging water.

In French Patent No. 2,104,941 filed 9th Sept., 1970, applicant describes sealing means of the type having a perforated diaphragm fixed to the frame of the machine and to a sealing ring rubbing against the sleeve and in which the diaphragm is provided with at least one orifice opening into a pressure compensating chamber located on the other side of the diaphragm relative to the water so that the water pressure prevailing in the water jacket between the sleeve and the mould is balanced on each side of the diaphragm, whereby the pressure of application of the sealing ring rubbing against the sleeve is reduced and the wear of this ring and its braking effect are also reduced.

An object of the invention is to provide sealing means for a centrifugal casting machine which is improved in such manner that the rubbing sealing ring is subjected to an adjustable pressure of water so as to improve the cooling of the shell without this resulting in excessive wear of the ring or an excessively high braking effect.

The invention provides sealing means which comprise a diaphragm integral with the frame of the machine and a sealing ring rubbing against the sleeve, the diaphragm and the ring defining a chamber around the mould of the machine, wherein the diaphragm is constituted by a flexible wall of a chamber whose opposed rigid wall has extending therethrough an inlet pipe supplying water at adjustable pressure and a water outlet pipe, one of the faces of the diaphragm being inside said chamber whereas the other face is integral with the sealing ring and the part of said other face defined by the ring is in the water jacket.

Owing to this arrangement, the diaphragm, which is subjected on one of its faces to the adjustable water pressure and on a part of the other face to the pressure of the water jacket, exerts a moderate force on the sealing ring rubbing against the sleeve.

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

In the drawing:

FIG. 1 is a diagrammatic sectional view of a machine for centrifugally casting metal pipes comprising a plurality of sealing means according to the invention;

FIG. 2 is a detail sectional view, to an enlarged scale, of two of the sealing means pertaining to one of the rings, and

FIG. 3 is a partial radial longitudinal sectional view of a modification of the casting machine.

In the illustrated embodiment, the invention is applied to a machine for centrifugally casting metal pipes. The machine comprises in the known manner a carriage which is movable in translation. This carriage comprises a frame 1 within which is mounted a rotary centrifugal casting mould or shell 2 having an axis XX. This mould is surrounded by a sleeve 3 which is coaxial with and connected to rotate with the mould.

The sleeve 3 defines with the mould 2 a double wall whose annular space 4 is adapted to be filled with cooling water and thus constitutes a water jacket.

The mould 2 and the sleeve 3 are rotated by a motor 5. The cooling water supplied by an exterior supply circuit enters and issues from the end of the carriage by way of pipes 6. These pipes connected to the exterior circuit extend through the frame 1 and communicate with either one of two annular members 7 which are fixed to the frame 1 and are concentric with the sleeve 3 and the mould 2 and have a U-shaped cross section.

The members 7 each define an annular chamber 8 which communicates with the annular space 4 by way of an opening 9 in the sleeve 3 located in the region of the corresponding pipe 6.

Sealing means according to the invention are provided between each flange of each fixed annular member 7 and the rotary sleeve 3. The machine comprises therefore four sealing means J J J 1,. In this machine the water jacket is restricted to the annular space 4 and the chambers 8.

Each sealing means mounted between one of the flanges of the fixed outer annular member 7 and a flange 10, which is a rubbing flange and integral with the rotary sleeve 3, is constructed in the following manner (FIG. 2).

Each flange of the member 7 is extended radially toward the axis X--X by a rigid partition wall 11 and carries, at a certain axial distance from the rigid wall 11 and roughly parallel to the latter, a flexible annular diaphragm 12 for example of elastically yieldable material such as rubber. The diaphragm 12 is fixed to the wall 11 along its inner peripheral edge portion by means of an annular boss 11 and an axial spacer ring 11'. The diaphragm 12, thus maintained in facing relation to the partition wall 11, defines with the latter an annular chamber 13 termed a pressure chamber. The diaphragm 12 carries. outside the chamber 13 a sealing ring 14 having dimensions intermediate between the inside and outside diameters of the chamber 13. The ring 14 is of friction material for example of metal alloy or of organic material such as that known under the trade name CELORON. Itis fixed to the diaphragm 12 by, for example, screws 15. It is adapted to be applied in a fluidtight manner against the flange 10 so as to close this end of the water jacket surrounding the mould 2.

Communicating with the pressure chamber 13 is a tubular inlet pipe 16 supplying water under adjustable pressure and a tubular outlet pipe 17 for discharging this water. The water pressure, measured by a pressure gauge 18, is controlled by a valve 19 both of which are inserted for example in the outlet pipe 17. The

pipes

16 and 17, which are rigid and constitute a fixed water circuit in which the water is under adjustable pressure mounted on the frame 1 of the machine, are connected to flexible pipes 20 and 21 (FIG. 1) for supplying and discharging the water, these pipes being necessary owing to the fact that the machine is movable in translation.

The sealing means operate in the following manner:

When the water arrives at pressure P by way of one of the pipes 6, it flows for example in the direction of arrows 1 into the corresponding annular chamber 8 and into the annular space 41 in which it forms a water jacket around the mould 2. It issues in the direction of arrow 1 by way of the other annular chamber 8 and leaves the machine by way of the pipe 6 of the other end of the carriage.

In the region of each sealing means J J the water is in contact with the outer face of the diaphragm l2 and with the sealing ring 14. Simultaneously each pres sure chamber 13 is filled with water at pressure p. Preferably, pressure P exceeds pressure p. For example, pressure P is of the order of 5-6 bars and pressure p of the order of 1.6-1.8 bars. Pressure P is maintained in the circuit comprising the

pipes

16 and 17 and the chambers 13 by means of the valve 19 and can be read off the pressure gauge 18. Each flexible diaphragm 12 is therefore subjected on its inner face pertaining to the chamber 13 (face 8,) to pressure p and on a part of its outer face (face S to pressure P. A pressure balance is achieved owing to the fact that the diaphragm 12 transmits to the water jacket 4 pressure P while applying the sealing ring 14 against the flange with a force which is equal to the product of the pressure multiplied by the area of the face S1 of the diaphragm 12 pertaining to the chamber 13 minus the product of the pressure P of the water jacket multiplied by the area of the face S2 in contact with the water jacket inside the sealing ring 14.

When, on one hand, the speed of rotation of the mould 2 and sleeve 3 is increased and, on the other hand, the rate of flow of the liquid metal into the mould 2 is increased so as to increase the production rate, the machine tends to heat up and the water jacket tends to vaporize locally. Pockets of steam are liable to form which would stop the flow of the water in the direction of arrows fl and f2 so that the machine would no longer be suitably cooled and production would be affected. The mould 2 would moreover be subjected to harmful thermal stresses which could rapidly put it out of service. In order to avoid these serious drawbacks the pressure of the cooling water in the annular space 4 is increased.

In this way formation of pockets of steam are avoided and a good cooling is ensured even if the acceleration of the production results in increased heating. However, in order to avoid correspondingly increasing the force of application of the sealing rings 14 on the flanges l0 and thus avoid increasing the braking effect and wear of the rings 14, pressure P in the chambers 13 must be increased.

Thus, the rubbing of the sealing rings 14 against the flanges 10 remains acceptable since the braking effect is negligible. Indeed, the force of application of each sealing ring 14 against the corresponding flange 10 exerted by the water in the pressure chamber 13 on face S1 is reduced by the opposing force from the pressure of the water jacket which is exerted on face S2 of the diaphragm which is smaller than face S1.

Consequently, owing to the invention, rotation of the mould 2 and sleeve 3 for starting up is more rapid and the speed of rotation for centrifugal casting is reached quicker owing to the fact that it is possible to control the pressure of application of the sealing rings 14 on the flanges 10. It is even possible to increase the pressure P of the water jacket 4 in the course of an increase in the rate of production without increasing the force of application of the rings 14 on the flanges 10 and consequently without increasing the power required from the motor 5 for driving the mould 2.

By way of modification, instead of having four identical sealing means of the type according to the invention in a centrifugal casting machine there may be provided only two sealing means J1 and J2 (FIG. 2) at one end of the machine and two different sealing means, for example of the type described in Applicant's aforementioned French Patent No. 2,104,941.

Note that the machine just described is of the dry frame" type since the space between the frame 1 and the sleeve 3 between the sealing means J2 and J3 is devoid of water. Now, the invention is also applicable to machines of the so called wet frame" type, that is, in which the water jacket is extended to the whole of of the annular space between the mould 2 and the frame 1. In this case, it is sufficient to provide two sealing means such as J1 and J4 between the frame 1 and the mould 2 and between the frame 1 and the sleeve 3 at the ends of the machine.

According to another modification shown in FIG. 3, instead of supplying the circuit 16-17 with water at an adjustable pressure from a fixed station connected to the

pipes

16 and 17 by

flexible pipes

20 and 21, a water circulating pump 22 may be mounted on the frame 1 of the machine.

In this case, the circulating pump 22 draws in the water from the mains and discharges the cooling water at pressure P into one of the pipes 6 (inlet) to which the pipe 16 is connected. The pipe 17 communicates with the surrounding air for discharging the water. The pipe 16 is connected to the other pipe 6 (outlet) at the other end of the machine, whereas the corresponding pipe 17 is connected to the surrounding air for discharging the water.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. Sealing means for a centrifugal casting machine, the machine having means defining a frame, a mould and a sleeve, the mould and sleeve being coaxial and rotatable in the frame and defining an annular space for mould cooling liquid, inlet means and outlet means for supplying cooling liquid to the annular space, the sealing means comprising an elastically yieldable annular diaphragm having an outer peripheral annular portion, an inner peripheral annular portion and an intermediate annular portion, means for securing the outer and inner peripheral portions of the diaphragm to the frame in a fluidtight manner, a sealing ring secured to one face of the diaphragm in the intermediate portion of the diaphragm for sliding sealing contact with the sleeve, the sealing ring defining on said one face of the diaphragm an elastically yieldable annular portion of the diaphragm for communication with the annular space and exposition to the pressure of the cooling liquid, rigid means for securing to the frame and defining a chamber with a face of the diaphragm opposed to said one face, and means for putting the chamber in communication with a source of fluid under pressure.

2. Sealing means as claimed in claim 1, further comprising means for adjusting the pressure of the fluid of said source.

3. A machine for centrifugally casting metal pipes comprising means defining a frame, a mould, a sleeve, the mould and sleeve being coaxial and rotatable in the frame and defining an annular space for mould cooling liquid, inlet means and outlet means for supplying cooling liquid to the annular space, and sealing means located at at least one end of the sleeve, the sealing means comprising an elastically yieldable annular diaphragm having an outer peripheral annular portion, an

inner peripheral annular portion and an intermediate annular portion, means for securing the outer and inner peripheral portions of the diaphragm to the frame in a fluidtight manner, a sealing ring secured to one face of the diaphragm in the intermediate portion of the diaphragm for sliding sealing contact with the sleeve, the sealing ring defining on said one face of the diaphragm an elastically yieldable annular portion of the diaphragm communicating with the annular space and exposed to the pressure of the cooling liquid, rigid means secured to the frame and defining a chamber with a face of the diaphragm opposed to said one face, and means for putting the chamber in communication with a source of fluid under pressure.

4. A machine as claimed in claim 3, wherein the sleeve has an outer flange defining an annular radially extending inner face in sealing contact with the sealing ring.

5. A machine as claimed in claim 3, wherein the radial dimension of the sealing ring is less than the radial dimension of the intermediate annular portion of the diaphragm.

6. A machine as claimed in claim 3, wherein the source of fluid under pressure comprises liquid pumping means mounted on the frame.

Claims

3. A machine for centrifugally casting metal pipes comprising means defining a frame, a mould, a sleeve, the mould and sleeve being coaxial and rotatable in the frame and defining an annular space for mould cooling liquid, inlet means and outlet means for supplying cooling liquid to the annular space, and sealing means located at at least one end of the sleeve, the sealing means comprising an elastically yieldable annular diaphragm having an outer peripheral annular portion, an inner peripheral annular portion and an intermediate annular portion, means for securing the outer and inner peripheral portions of the diaphragm to the frame in a fluidtight manner, a sealing ring secured to one face of the diaphragm in the intermediate portion of the diaphragm for sliding sealing contact with the sleeve, the sealing ring defining on said one face of the diaphragm an elastically yieldable annular portion of the diaphragm communicating with the annular space and exposed to the pressure of the cooling liquid, rigid means secured to the frame and defining a chamber with a face of the diaphragm opposed to said one face, and means for putting the chamber in communication with a source of fluid under pressure.