US3587712A

US3587712A - Rotary carrier method and apparatus for centrifugal casting

Info

Publication number: US3587712A
Application number: US770507A
Authority: US
Inventors: Alan Dearden; Edgar O G Castell; Leslie Hylton
Original assignee: Hepworth and Grandage Ltd
Current assignee: Federal Mogul Bradford Ltd
Priority date: 1967-10-30
Filing date: 1968-10-25
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28
Also published as: GB1239926A; FR1587293A; DE1805163A1; CH471618A

Abstract

THE DISCLOSUTE RELATES TO A CENTRIFUGAL CASTING APPARATUS AND PROCESS WHEREIN DIES ARE DISPLACED AROUND A CIRCULAR PATH BETWEEN CASTING AND EJECTION STATIONS BY A CARRIER, THE DIES AND THE CARRIER BEING ROTATABLE ABOUT HORIZONTAL AXES.

D R A W I N G

Description

United States Patent Inventors Appl. No.

Filed Patented Assignee Priority Alan Dearden;

Edgar O. G. Castell; Leslie Hylton, all 01' St. John's Works, Bradford. England 770,507

Oct 25, 1968 June 28, 1971 Hepworth & Grandage Limited Bradford, England Oct. 30, 1967 Great Britain ROTARY CARRIER METHOD AND APPARATUS FOR CENTRIFUGAL CASTING 11 Claims, 2 Drawing Figs.

US. Cl

Int. Cl

[50] FieldofSearch .1 164/114, 154, 286, 292, 295-298, 323-325, 138

[56] References Cited UNITED STATES PATENTS 2,023,040 12/1935 Adams l64/298X 2,570,325 10/1951 Dalton... 164/295 2,943,369 7/1960 Szwed [64/154 3,419,066 12/1968 Lorang 164/154X 3,457,986 7/1969 Andrews 164/295X 3,486,551 12/1969 Inoye 164/286 Primary Examiner-J. Spencer Overholser Assistant Examiner-12. Spencer Annear Atlorney-Holcombe, Weterill and Brisebois ABSTRACT: The disclosure relates to a centrifugal casting apparatus and process wherein dies are displaced around a circular path between casting and ejection stations by a carrier, the dies and the carrier being rotatable about horizontal axes.

ROTARY CARRIER METHOD AND APPARATUS FOR CENTRIFUGAL CASTING This invention relates to centrifugal casting.

According to this invention in one aspect, a centrifugal casting apparatus includes, or is adapted to accommodate, a plurality of dies, means to move each die between a casting station and an ejection station, means to rotate a die when located at the casting station to effect centrifugal casting of a molten metal in the die, and means to eject a solidified casting from a die when located at the ejection station. The dies, for example, a pair of dies, are preferably located with their rotational axes disposed substantially horizontally, and are movable around a circular or part-circular path having a horizontal axis.

According to this invention in yet another aspect, a centrifugal casting process includes moving a plurality of rotata ble dies in unison around a circular path having a horizontal axis, successively to a casting station whereat each die is rotated to effect centrifugal cast of molten metal poured into the die, and then to an ejection station whereat the casting previously formed within the die is ejected therefrom.

One embodiment of the centrifugal casting machine in ac cordance with the invention will now be described with reference to the accompanying drawings, of which:

FIG. 1 is a diagrammatic plan view, partly in section, of the machine; and

FIG. 2 is a section of the line A-A on FIG. 1.

The machine includes a frame 11 in which is mounted a carrier l2 rotatable about a horizontal axis. The frame 11 includes

plane end walls

13, 14 which are interconnected by the base and by an interconnecting wall 15 which is curved and forms the sides and top of the frame. The wall 15 is provided with ports for observation.

The carrier includes a shaft 16 mounted in bearings l7, 18 in the end walls, to allow the shaft 16 to be rotated and also to allow it to be moved axially for a limited travel. A torque unit 19 mounted on one end wall 14 is connected to the shaft to rotate it between predetermined angular positions, and a piston-and-cylinder device 20 mounted on the casing of the torque unit 19 is connected to the shaft 16 to move it axially for a limited travel relative to the frame 11.

Secured to the shaft 16 are a pair of

transverse plate members

21, 22 each of which is provided with a pair of apertures 23 on diametrically opposite sides of the shaft 16, and each aperture contains an interchangeable liner 23a. The apertures defined by the liners carried by the plate member 21 are aligned with the corresponding apertures of the liners carried by the plate member 22.

When the carrier 12 is in the operating position, the centers of the two aligned pairs of apertures and the rotational axis of the shaft 16 are in a horizontal plane. The region of one aligned pair of apertures in this position will be referred to as the pouring and casting station, and that of the other aligned pair of apertures as the ejection station. The carrier 12 carries a pair of cylindrical castiron dies 24, 25, one in each pair of apertures, with a clearance between the outside of the die and the apertures for a reason which will become apparent, the dies being positioned with their axes of rotation disposed generally horizontally.

Both ends of the two

dies

24, 25 are formed with a conical taper 26; at the pouring station there are provided a pair of conical members or

rings

27a, 28a, one of which 27a will be referred to as the movable cone and the other of which 28a will be referred to as the fixed cone. The rotational axes of these cones are aligned with one another and with the centers of that aligned pair of apertures 23 and liners 23a located at the pouring and casting station.

The movable cone 27a forms part of an assembly, indicated generally at 27, and in particular, is interchangeably mounted on three equiangularly spaced pillars or webs 27b rigid with a base plate 270 mounted on a shaft rotatable by an electric motor 29. This assembly and motor 29 are axially movable with respect to end wall 14 by means of a pneumatic ram device 30. The motor 29 may be mounted in suitable slides on the base. The fixed cone 28a is likewise interchangeably mounted on three equiangularly spaced pillars or webs 28b rigid with a base plate 28c carried by a shaft rotatably mounted in a bearing carried by end wall 13, so as to be fixed against axial movement. The fixed cone 28a, its base plate 280 and mounting shaft have a large-diameter hollow bore, and a tipping ladle 31 for the molten metal to be cast is mounted to be movable so that its spout 32 can be advanced through this hollow bore, beyond the cone 28a, and inclined in order to pour the metal within the die 24. The cone angles of the movable cone 27a and of the fixed cone 28a are such as to cooperate with the conical tapers 26 in the ends of the dies.

At least the surfaces of the

cones

27a, 28a which are likely to come into contact with molten metal during casting, and in particular to conical surfaces, and the opposed inwardly directed faces thereof, are preferably coated with a deposit of a material which prevents or minimizes the adhesion of the cast metal to the cones, for example, a 0.005 inch thick plating of industrial chromium.

At the ejection station there is provided an ejector in the form ofa disc 34 mounted on the end of the rod ofa linear actuator 35 and having a diameter smaller than the internal diameter of the dies; the central axis of the disc 34 and actuator 35 is spaced slightly below the horizontal plane containing the axis of rotation of the carrier 12, because at this station the die 25 rests on the surface of the apertures 23 in the

transverse plate members

21, 22, and is therefore not concentric with the apertures. The disc 34 can be advanced for substantially the whole length of the die 25, to horizontally eject a solidified casting from the die. For this purpose an aperture 36 is provided in the end wall 13, and a platform 37 is conveniently provided on the outside ofthe end wall to receive the casting.

The rod of actuator 35 is hollow and is arranged to be fed with a supply of compressed air when it leaves its position of rest and is advanced through the die, by means, for example, of a port which is brought into register with a suitable air source. The interior of the rod is connected to small holes, or jets, 38 in the periphery of the disc 34, so that substantially the whole interior of the die 25 is swept with compressed air during the ejection stroke.

Adjustable stop means are provided in order to prevent the dies from being displaced horizontally with the castings during ejection. These means comprise three blocks 39 carried by stub shafts 40 journaled in the end wall 13 around the hole 36. Mounted on each stub shaft 40 outside the end wall is a double-ended lever 41, one end of which is connected to its associated block 39 by a support arm 42, and the other end of which is apertured to locate on a selected one of a number of fixed pins 43 carried by a plate 44 secured to the end wall 13. It will thus be apparent that each lever 41, and therefore each block 39 may be adjusted in inclination, by predetermined amounts, thus adjusting the distance by which the blocks project, into the space between the hole 36 and adjacent end of the die 25.

A fluid logic unit, diagrammatically indicated at 33A, 33B is provided for the purpose of detecting whether or not a casting, after solidification, has detached from the fixed cone 280 or not, on withdrawal of the die 24 in carrier 12. The unit may include an air emitter 33A, and a receiver 338, which will detect the jet from the emitter 33A provided the casting has detached correctly; if the jet is obliterated by the casting, the receiver 338 will provide appropriate action for example, will prevent continuation of the casting sequence until the fault is rectified.

The operation of the machine will be described assuming that the carrier 12 has just been rotated to bring the die 24 of the two dies to the pouring and casting station.

The carrier 12 is then moved forward (to the right as shown in FIG. 1) by the piston-and-cylinder device 20 to ensure that the die 24 overlaps the fixed cone 28a. The assembly including the movable cone 27a and driving motor 29 is then moved forward (to the right as shown) to engage the tapers 26 on the ends of the die 24 on the respective fixed and

movable cones

27a, 28a in doing so the die 24 is moved from the position in which it rests in the carrier 12 upward to a position in which it is concentric with the axis of rotation of the

cones

27a, 28a. The movement of the assembly including movable cone 27a starts a short second)time delay device, which device, at the end of the time delay, closes a contactor in circuit with motor 29.

The motor 29 is energized, and rotates the die 24, the drive being transmitted as a result of the die being gripped between the fixed and

movable cones

27a, 28a of which the movable cone 27a is driven by the motor 29. The operator then dresses the die manually with a suitable dressing, ofa type well known in the art, by inserting a tube through the hollow bore of the fixed cone 28a, and upturning the tube to deposit the dressing within the rotating die 24.

The ladle 31 which contains the molten metal is then advanced, by the operator, the spout 32 passing through the hollow bore of the fixed cone 28a, and the molten metal is poured. The spout 32 is then withdrawn, and this action may start a timing device which is set to allow time for solidification of the metal. Alternatively the operator may start the timing device manually by means ofa pushbutton. I

At the end of the timed period, when the metal has solidified, the motor 29 is automatically stopped and a magnetic brake applied. The movable cone 27a and motor 29 are then retracted by pneumatic ram 30, and the carrier 12 is moved back by the piston-and cylinder device to ensure that the die 24 is free of the fixed cone 28a and is clear thereof. This enables the die 24, containing the casting, to move down and rest on the lower surface of the apertures in the liners 23a carried by the

members

21, 22 of the carrier 12.

An interlock is provided to ensure that the movable cone 27a is not removed until rotation has ceased; moreover the

fluid logic device

33A, 33B ensures that the casting has freed itself from the fixed cone. lf this has not occurred, the next stage of the operation cannot take place.

The carrier 12 is then rotated by the torque unit 19 to bring the die 24 to the ejection station, i.e. to the position in which the die is shown in the drawings. Arrival of the die 24 at this station initiates a second timing device (for example by closing a switch) which allows a short cooling period for the casting at the ejection station to contract away from the die 24 before ejection.

Under control of the second timing device, the ejector 34 is moved outward by the actuator 35 to eject the solidified casting from the die 24 at the ejection station between the blocks 39 and through the aperture 36 in the end plate 13 of the frame onto the platform 37 from which it is removed by the operator. The die 24 is prevented from moving towards the aperture 36 during ejection by abutment of the die with the end faces of the blocks 39. Compressed air is ejected from the jets 38 on the periphery of the ejector disc 34 at the same time as the ejector is advanced, to clean the interior of the die 24, and the ejector 34 is then retracted again.

The carrier 12 is now free to rotate to bring the die 24 back to its initial position at the pouring and casting station (i.e. to the position in which die 24 is shown in FIG. 1).

Since the

cones

27a, 28a, are coated with chromium, to which the cast metal is not prone to adhere, the likelihood of the solidified casting adhering to one or both cones is eliminated or reduced. Moreover, due to the fact that the cones are formed'as rings, and are mounted on, but spaced from, their associated base plates 27a, 280, by pillars 27b, 28c, cooling air is free to circulate around these components, thereby substantially reducing detrimental transfer of heat from the die to the shafts carrying the base plates, and their associated journals.

The apparatus hereinbefore described is particularly compact, due to the fact that the dies move around a circular path between stations. It may be operated continuously and automatically, and enables castings to be produced at a high rate. The ejection of the finished castings onto the platform 37 renders the apparatus particularly suitable for incorporation in an automatic system or production line.

The apparatus may be readily adapted to accommodate dif-. ferent diameters of dies, by exchanging the

cones

27a, 28a, by different size cones, and by replacing the liners 23a by liners having different internal diameters, i.e. internal diameters slightly larger than the external diameters of the replacement dies, so that the dies will not bind in the liner due to thermal expansion ofthe dies during casting.

The inclination of the blocks 39 at the ejection station may be adjusted so that their radially inner tips engage the ends of the replacement dies, but do not extend into the path of castings ejected therefrom, during operation of the apparatus. These blocks 39 are swung out of the way during removal and replacement of the dies, which is effected through the aperture 36.

It will be understood that the arrival of one die at the ejection station is simultaneous, in the embodiment described, with the arrival of the other die at the pouring and casting station; thus the sequence of operations at the ejection station, as just described, takes place concurrently with the sequence of operations at the pouring and casting station which were described above.

Although the machine has been described as having two dies 24, 25 it will be evident that the carrier 12 might be arranged to have, for example, four pairs of aligned apertures 23, each carrying a die. In such an arrangement the stations could be arranged at intervals of rotation of the carrier 12, and the two stations between the pouring station and the ejection station might be employed to provide a cooling period for the casting. in this way time delays at the pouring and ejection stations may be reduced. If desired, pouring of the molten metal, and rotation of the die to effect centrifugal casting, may be effected at different stations instead of the same stations as specifically described.

Although, as will be apparent from the arrows in H6. 2, the carrier in the embodiment specifically described is rotated in a single direction, for example, clockwise as viewed in FIG. 2, the carrier may be rotated in the opposite direction, or oscillated back and forth between the stations.

We claim:

1. Centrifugal casting apparatus including a plurality of dies constrained to move in unison along a generally circular path, between a casting station and an ejection station, by a carrier rotatable about a generally horizontal axis, means to rotate a die about an axis generally parallel to the rotational axis of the carrier, when the die is located at the casting station, to effect centrifugal casting of molten metal in the die, and means to eject a solidified casting from a die when located at the ejection station, the carrier being provided with apertures within which the dies are loosely cradled, the apparatus further including die support means at the casting station, rotatable by the drive means, and adapted to releasably support a die at each end thereof, the support means comprising a pair of members each having a conical surface cooperable with a corresponding end surface of the die, means for'displacing said conical members toward each other to clamp and support the die therebetween, the axis of a die, when cradled by the carrier at the casting station, being disposed below the axis of rotation of the conical members, the conical surfaces of the conical members upon clamping of the die, cooperating with the end surfaces of the die to lift the die out of contact with the carrier to a position in which said axes are coincident, and also to transmit to the die, rotation imparted by the drive means to the support means.

2. Apparatus as claimed in claim 1, wherein the conical members are dimensioned to fit into the ends of the die and to cooperate with correspondingly tapered internal end surfaces of the die.

3. Apparatus as claimed in claim 2, wherein the first of said conical members is coupled to an electric drive motor to rotate the die, and the second of said conical members is axially fixed but freely rotatable, and provided with an axial passage extending therethrough, means being provided to pour molten metal into a die during rotation thereof at the casting station, through the passage.

4. Apparatus as claimed in claim 3, wherein the first conical member and its drive motor, are bodily reciprocable, by means of a hydraulic ram, to axially advance or withdraw said first conical member relative to the die and second conical member.

5. Apparatus as claimed in claim 4, wherein the carrier is axially reciprocable relative to the second conical member to advance or withdraw a die cradled by the carrier at the casting station, relative to the second conical member.

6. Apparatus as claimed in claim 5, wherein each conical member comprises a ring, at least those surfaces thereof which come into contact with molten metal during casting being coated with chromium, the ring being detachably mounted on pillars carried by a base plate rotatably supported by the apparatus frame in journals, said pillars spacing the ring from its associated base plate, whereby heat transfer from the ring to the journals during operation of the apparatus is minimized.

7. Apparatus as claimed in claim 6, wherein the carrier is adapted to carry two demountable and interchangeable dies located in a generally diametrically opposed relationship on opposite sides of the rotational axis of the carrier, and comprises a shaft journaled in the frame of the apparatus, about the axis of which the carrier is rotatable, a pair of transverse plate-members secured to and spaced along the shaft, each plate-member being provided with a pair of apertures or diametrically opposed sides of the shaft, the apertures in one plate-member being aligned with corresponding apertures in the other plate-member, and each aperture containing a detachable and interchangeable annular liner.

8. Apparatus as claimed in claim 7, wherein the casting and ejection stations are disposed in a common horizontal plane.

9. Apparatus as claimed in claim 8, wherein an ejector ram is located at the ejection station, adapted to enter one end ofa die when located at said station to eject a solidified casting therefrom and through an aperture in the frame of the apparatus, stop means being provided adapted to engage a die to prevent displacement thereof with the casting during ejection, said stop means comprises a plurality of stops journaled in the frame at spaced positions around the aperture for swinging movement toward and away from the axis of the die, the stops projecting between the die and aperture.

10. Apparatus as claimed in claim 9, adapted for automatic repetitive operation, said apparatus including control means, to synchronize and control the operating cycles of the various components of the apparatus, including a casting sensing means at the casting station operable and adapted to prevent rotation of the carrier upon detection of a solidified casting adhering to one of the conical members, said sensing means comprising a fluid logic unit including an air emitter and a receiver associated therewith, the receiver being screened from the emitter unless a space exists between the fixed conical member and the die or a solidified casting therein.

11. A centrifugal casting process, including moving a plurality of rotatable dies in unison around a circular path having a horizontal axis, successively to a casting station whereat each die is rotated about an axis parallel to said horizontal axis to effect centrifugal casting of molten metal poured into the die, and then to an ejection station whereat the casting previously formed within the die is ejected therefrom, the die being loosely cradled, and carried around the circular path, on a carrier, each die, when at the casting station, being releasably clamped by its opposite ends between a pair of relatively axially displaceable conical members of die support means located at the casting station, raised out of engagement with the carrier, as a result of the clamping action, rotated about its rotational axis via the die support means, whilst molten metal is poured thereinto through one end of the die, the rotation then being stopped and the die replaced on its carrier prior to transfer by the carrier to the ejection station.