US3174199A

US3174199A - Method for centrifugal casting and apparatuses for practising it

Info

Publication number: US3174199A
Application number: US109339A
Authority: US
Inventors: Trindler Friedrich
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-05-11
Filing date: 1961-05-11
Publication date: 1965-03-23
Anticipated expiration: 1982-03-23
Also published as: DK106397C; CH401369A; GB931174A

Description

March 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING IT Filed May ll, 1961 8 Sheets-Sheet 1 N V EN 70/? FRIEDRICH T/?/ N OLE? March 23, 1965 F. TRINDLER 3,

mm'mon FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING rr Filed May 11, 1961 s Sheets-Sheet 2 NVENTOfi F Rl DR/CH Til/VOL ER A TTORNEYS March 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING IT Filed May 11, 1961 a Sheets-Sheet 4 /N VEN TOR FR/EbR/C'H TAiA/DZ En B/WWPWM ATTD/IIY V March 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIFUGAL CASTING AND APPARATUSES FOR FRACTISING IT Filed May 11, 1961 8 Sheets-Sheet 5 lNvE'A Ta F P/EDIFICH TAINDLE F TTORNEY March 23, 1965 F. TRINDLER 3,174,199

METHOD FOR CENTRIFUGAL CASTING AND APPARATUSES FOR PRACTISING IT a Sheets-Sheet 6 Filed May 11, 1961 I N v E NTOR FRIEDRICH TRINDLEIY XMzZM QLJ A T7'ORNEY! March 23, 1965 F. TRINDLER 3,174,199 7 METHOD FOR CENTRIF'UGAL CASTING AND APPARATUSES FOR PRACTISING IT Filed May 11, 1961 s Sheets-Sheet a FIG.8

ATTORNEYS United States Patent 3,174,199 METHOD FOR CENTUGAL CASTING AND APPTUSES FOR PRACTISING IT Friedrich Trindler, Bachtalstrasse I6, Ennethaden, Switzerland Filed May 11, 1961, Ser. No. 169,339 Claims priority, application Sweden, May 11, 196%, 4,646/ 60 12 Claims. (Cl. 22-65) This invention relates to a method for centrifugal casting of molten materials, preferably metals such as iron and steel, nonferrous metals and metal alloys, in a twopart or multipart mould which is rotated during casting.

The method generally applied in such centrifugal casting implies that a new article cannot be cast in the mould until the next preceding article has set and/or cooled sufiiciently to permit lifting out of the mould and until the mould, after opening thereof and removal of the cast article, has again been closed to a state ready for casting. The cooling and removal of the cast article requires a relatively long time and therefore has an inhibitory effect on the continuous casting operation and on the automatisation of the casting method.

To overcome these disadvantages it is suggested according to the present invention to use a method for centrifugal casting of molten materials in a two-part or multipart mould which is rotated during casting, and this method is characterized by carrying away the cast article, after it has set sufliciently to permit dividing the mould, in one of said mould parts as a support, and then assem bling a mould part identical to said mould part with the rest of the mould to form a complete mould which is fully ready for casting of a new article while the earlier cast article cools down in, and/or is removed from, the mould part accommodating it. While an article just cast sets to the strength necessary to permit its removal from the mould, further articles can thus be cast at a speed determined by the pouring of the material to be cast and by the operations for separating and assembling the mould to a state ready for casting, whereas the remaining setting and/ or the necessary cooling to permit removal of one of the articles cast from the mould does not unfavourably affect the speed at which the casting takes place. What is more, the pouring can be done all the time at one and the same place, viz. where the rest of the mould is posi tioned, which dispenses with any transport between each pouring operation.

For practising the novel method the invention provides an apparatus for centrifugal casting of molten material with the use of at least one two-part or multipart mould which is rotated during casting. This apparatus is characterized by the fact that two or more identical mould parts are disposed on at least one supporting mechanism and can be assembled one at a time by said mechanism with the rest of the mould to form a complete mould fully ready for casting.

For a better understanding of the invention a number of examples will be described in the following with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic plan view of an apparatus according to the invention;

FIG. 2 is a vertical section of the mould parts and a gripping mechanism adapted to lift the cast articles out of the mould, and diagrammatically illustrates different phases of the method according to the invention;

FIG. 3 is a vertical sectional View, partly in side elevation, of an embodiment of the apparatus;

FIG. 4 is a plan view of the apparatus shown in FIG. 3;

FIG. 5 is a vertical sectional view, partly in side elevation, of a further embodiment of the apparatus;

FIG. 6 is a horizontal sectional View of the apparatus 3,174,199 Patented Mar. 23, l65

ice

shown in FIG. 5, partly in section on line VI-VI in FIG. 5;

FIG. 7 is a vertical sectional view, partly in side elevation, of still another embodiment of the apparatus;

FIG. 8 is a side elevational view of the appanatus shown in FIG. 7.

First, the method according to the invention will be explained in more detail with reference to the diagrammatic FIGS. 1 and 2. Mounted on the upper side of a supporting mechanism in the shape of a preferably horizontal disk (turntable) 10 adapted to turn about its center, are four lower mould parts 13a-13d which are identical. The disk 10 is provided along its periphery with a gear rim 11 which meshes with a gear 12 driven by a drive motor. Each of the lower mould parts 13ad is mounted for rotation on the disk 10 and adapted to be rotated by an individual drive mechanism. By intermittent rotation of the disk 10 in steps of each, the four lower mould parts 13a-d are movable in turn of order to four different stations designated 1-1! in FIGS. 1 and 2. When so moved the mould parts can be brought in position directly beneath an upper mould part 14 (FIG. 2) located in station I and mounted for rotation above the disk 10. The upper mould part 14 is preferably disposed in a frame (not shown) and rotatable by an individual drive. To assemble the mould part 14 with that mould part (FIG. 1) which is beneath it, to form a complete mould ready for casting, the disk 10 with the mould parts 13ad thereon or the mould part 14 can be axially shiftzable. Means (not shown) are arranged above the mould part 14 for pouring molten material into the closed mould in station I. A gripping mechanism 15 (FIG. 2) is disposed in station IV above the disk 10 to remove the finished castings from the mould, and said mechanism is carried by a supporting device (not shown) by means of which it is shiftable to a position beyond the periphery of the disk 14 above a conveyor (roller track) 16. The gripping mechanism may, however, also be stationary and there may be provided one or more means to move the castings from the gripping mechanism to a hot working station or a transit store.

With the disk 10 in the position shown in FIG. 1 the mould part 13a and the mould part 14a are situated opposite one another and can therefore be closed to form a mould ready for casting. The mould is now caused to rotate, if this has not been done already before the closing of the mould, and material to be cast is poured into the mould while it is rotating. After the material poured into the mould has set suiiiciently in order not to be thrown out of the mould when this is opened the mould parts 13a and 14 can be slowly separated whereupon the casting (designated 17 in all occurrences in FIGS. 1 and 2) is moved, while lying in the mould part 13a which is still held in rotation, from station I to station II by a rotation of the disk 10 through an angle equal to 90. By this rotation of the disk 10 the mould part 13a is simultaneously moved from station IV to station I and beneath the upper mould part 14 while the casting 17 in station II further sets and/ or obtains so high a strength that it may then be removed from the mould. In this way a new casting can simultaneously be cast in the mould formed by the mould parts 13d and 14 in station I. The procedure is repeated, the mould parts Ilia-d being advanced one step at a time corresponding to an angle of 90, and material to be cast is poured into the mould in station I during the stop period of the disk 10 between any two rotational steps. The castings 17 made in station I eventually arrive in station IV where they are removed from the corresponding lower mould part by means of the gripping mechanism 15 and are deposited for example on the conveyor 16 to be transported to other working stations.

For an optimum capacity of the casting apparatus the 5. number of mould parts on the disk can be selected in such a way that the time allowing the casting to set sufficiently and to be removed from the mould is longer than the time required forthe operations in-station I up to the'pouring of material to be cast into the mould. If the settingtime is say 120 seconds-and theoperations in station I (closing'themold, pouring the material to be cast, opening the mould and supplying a new mould part)take 40 seconds, there are thus required three steps for the successively set and/orreach-the'strength required for removing them from the mould. The fact that the mould parts are permanently held in rotation eliminates the time and energy losses which derive from a repeated braking and-acelerationof the mould parts. Therefore the grip ping mechanism 15 also must be arranged in such a way as to rotatesynchronously with the rotating-mould parts and that the gripping of the casting can take place at the same speed,.in order that the casting may be removed from the mould.

The method according to the invention naturally is not bound to the special arrangment diagrammatically shown in FIGS. 1 and 2, but canbe practised with apparatuses of different design It should be mentioned specifically that the rotary disk can be replaced by one or more other means for transporting the. lower mould parts between the differentstations, such as swingarrns, slides or carriages whichare guided on rails in a closed-circuit. In addition to the station in which the material to be cast is poured into the mould, and the stations in which'the casting cools down, up to the station in which the finished casting is lifted out of, or discharged from, the mould there may be arranged one or more stations'in which the mould parts are subjected to preliminary treatments, such as application of silicates, or provided-with prefabricated insets of refractory material or the like. Moreover, the axes of rotation of the mould parts may be arranged horizontally or in any position of inclination whatever between the vertical position'shown and horizontal position.

A structural embodiment of the apparatus outlined above in connection with the explanation-of the method according to the invention will now be described in more detail with reference-to FIGS. 3 and 4 in the drawings.

The apparatus shown therein is arranged in a chamber 29 for instance of concrete and comprises a rotary disk 21 which. is centrally mounted on a verticalupright 22 in said chamber for both rotational movement and shifting movement in the axial sense. For rotation of the rotary disk the latter is provided witha peripheral gear rim 23 which meshes with a gear 25 driven by a motor 24, alid for raising the rotary disk 21 single acting hydrauliccylinders 26 with piston rods 27 aremounted on the floor of the chamber 20, while lowering of the rotary'disk is brought about by its own weight. The gear 25 is of so large an axial length as to remain in mesh with the gear rim 23 in all height positions of the rotary disk 21.

A number of mould carriers for carrying lower mould FIGS, 3 and rier 28, and possibly to such mould carriers as may be arranged additionally. The mould carrier 28 is mounted for rotation by means of ball bearings 30 on a bushing 29 rigidly connected to the rotary disk 21. It is operatively connected over a drive belt 31 to a drive motor 32 on the rotary disk 21 and is braked by means of a brake belt 34. The drive belt 31 and the brake belt 34 act on a downwardly directed shell portion 33 of the mould carrier 28. The brake belt 34 has one 'endsecured in a fastening 35 arranged in fixed position on the rotary disk 21, and its other'end secured between the ends of a lever arm 36, which is mountedfor swinging movement on the rotary disk 21* in a point 37 at its one end, while it is operable at its otherend by means of a hydraulic cylinder 38 which is provided in the manner of a link between the last mentioned end of the lever arm 36 and a fixed point 39 on therotary disk 21. A circular 'annular lower mould part '40 is attached to the mould carrier 23; Disposed at the periphery of the'mould carrier 28 is a number of springs 28a which serve to elastically centerthe mould by means of'screws 28b! A flange sleeve 41is arranged in the upper portion of the chamber 20, and an upper mould carrier 42 is rotatably'mounted on said sleeve'41'by'means of'b'all bearings 43. Said mould carrier 42 has an upwardly directed shell portion 44 about which there are passed a belt 45'for driving the mould' carrier 42 and a brake belt 46 for braking it. The drive belt and the brake belt can be operatively connected with a motor and a brake applying device, respectively,-in themanne'rfshown for the'mould carrier 28, with the difierencdhowever, that the motor and the brake applying device 'for mould carrier 42 of course are stationarily mounted in thechamber 20, for instance at the underside of the upper wall thereof instead of being disposed on the rotary disk 21, as shown for mold carrier 28. A circular annular uppermould part 47 'is arranged beneath the upper mould'carrier 42,

and by raising the rotary disk 21 by means of the cylinders 26 said mould'part 47 can be closed against the mould part 40 to form a mouldready for casting, when 7 part dii'according to FIG' 3 is directly beneath part 47.

In the same manner the mould part 40" and further lower mould parts,'if any, can be caused to close separately against the mould part 47 to form-a mould ready for easting, as said lower mould parts are alternately movable into position beneath the mould part 47. The embodiment'in FIG. 3 is intended for water-cooled upper mould parts. with a water chamber 47:: and is fixedly connected to the mould carrier 42 via an annular intermediate portion 4715-61. The intermediate portion-is a flange with an upwardly tapering shell 47 b which via ribs 47c isintegral with an inner portion 47d and is fixedly connected-to'the mould carrier 42 so that the waterchamber 47a can be supplied with cooling medium through the annular space between 475 and 47d also during the rotation of the mould;

Cooling medium is poured onto the conical surface 47d by a pipe (not shown)-rrom where the medium flows into the cooling medium chamber 47a.

To prevent the cooling'medium from splashing upon rotation of the mold the supply conduit 47c is conical and 'wide'ns in a downward direction. Whenthe mold is stationary or slowly rotating the cooling-medium flows only over the conical surface 47d. At a higherrotational' speed of the mold it is possible that cooling medium-will be thrown away from the surface 47d and becaught by the tapering shell 4712] In the interior of the mould carrier 42 there is provided a supply pipe 48 lined with refractory material and rotatably mounted on the flangesleeve 41 by means of ball bearings 49 and 50. The pipe 48 is fixedly connected .to a pulley 51 which is drivable by means of a belt 52 from a drive motor 53. The pulley 51 is formed with an upwardly directcd flange54 about'which'is passed a brake belt 55 which is applied by means'of a brake applying device 56in the same manner as the abovementioned brake belt 34. The mouth end 57 of thesup- In this instance the mould part 47 is equippedply pipe 48 is bent in one direction in the peripheral sense, preferably in the direction opposed to the intended direction of rotation of the mould and the supply pipe in order that a calm flow of the melt into the mould may be obtained. However, the mouth may also be arranged more or less radially, and instead of being rotatable the supply pipe may naturally be stationary.

The upper end of the supply pipe 48 constitutes a continuous connection to a ladle 59 on the chamber 20 and is spaced a slight distance from the outlet opening 58. Naturally this outlet opening may be located in a holding furnace or melting furnace. To protect the jet of casting material between the ladle 59 and the pipe 43 from atmospheric influences there is arranged a cover 60 between the ladle 59 and the pulley 51, said cover having a sealing device 61 to the ladle 59 and a sealing device 61a to the pulley 51. Also provided in the cover 69 is a passage 62 through which a protective gas can be supplied, protecting the melt against oxidation, or through which passage evacuation can be effected. However, the melt can be protected against oxidation also by means of a gas screen in and per se known manner. The flange sleeve 41 contains a passage 63a for supplying cooling medium to the

chamber

63b and 63c between the relatively movable parts 41, 42, 48. For the same purpose fan blades may quite as well be provided at the outlet openings on top of the pulley 51 or at the underside of the support of the supply pipe 48. The supply pipe 48 has a further pipe 65 attached to and supported on its lower portion, the pipe 15 at 66 being in communication through a small slot with the pipe 67 to supply covering material or reagent. The closed mould parts 40 and 47 may be provided through this supply means with a coating before casting is done.

The connection at 66 is of such a known type that the pipe 65 is rotatable together with the supply pipe 48 relative to the pipe 67 disposed on the mould carrier 28. The pipe 67 is automatically separated from or connected to the pipe 65 at 66 when the mould carrier 28 with the bushing 29 on the rotary disk 21 moves to open and close the mould 40, 47, respectively. At the lower end of the pipe 67 there is provided a supply passage 682 in which is disposed a slide 68c movable by a cylinder 68a via a piston rod 68b for supplying predetermined quantities of material, for instance covering material, in the pipe 67. This material can then be conveyed, for instance by means of a compressed air pulse in a manner similar to that in pneumatic dispatch tubes, from a compressed air supply (not visible behind rotary disk 21) through a supply pipe 68d and through the

pipes

65 and 67 into the cavity of the mould formed by the mould parts 40 and 47.

A gripping mechanism for lifting the rings R cast in the apparatus out of the moulds and carrying them away from the apparatus is mounted above the lower mould carrier 28' and the lower mould part 40' carried thereby. The gripping mechanism is carried in its entirety by a slide 70 which is disposed in a guide 71 in the upper portion of the chamber 20 for movement in the horizontal sense. A hydraulic cylinder 72 for moving the slide 70 is arranged as a link between the slide and a fixed abutment 73 in the chamber 20. The supporting device of the gripping mechanism is a turntable 74 which is mounted for rotation in the slide 70 by means of a sleeve 75 and aball bearing 76. Passed about a flange 77 on the turntable 74 are a drive belt 78 for rotating the turntable 74 from a drive motor 79 on the slide 70, and a brake belt 80 which is fixedly anchored to the slide 81 and can be applied against the flange 77 by means of a hydraulic brake applying device 82 of substantially the same design as the earlier described brake applying device 36-39. Gripping jaws 84 are secured to a number of radially placed pull rods 83 each having a three-pronged fork, more precisely to the prong ends of said fork. At the underside of the turntable 74 the pull rods 83 are each guided in one guide 85 and have each of their prongs in a guide 86. Each pull rod 83 is provided at its end closest to the center of the turntable 74 with rotatably mounted rollers 37 which are inserted in T-grooves 88 in a conical clamping head 89'. This head has at its upper portion a stem 89 which is movable in the sleeve 75. The stem 89 is operatively connected to the piston rod of a hydraulic cylinder 90 for axially moving the head 39. As is readily seen, an axial movement of the head 89 results in a simultaneous shifting of the gripping jaws 84 radially in that said jaws are moved outwards at the downward shifting of the head and inwards at the upward shifting of the head. In the present instance the gripping jaws 84 are moved inwards to cause them to grip a ring R lying in the lower mould part 40, and outwards to deposit an earlier gripped ring. These functions, however, are also conceivable in the reverse direction. When the lower mould part 40' is in the raised position shown the gripping mechanism can thus be caused to grip the ring R, and after the lower mould part 40' has again been lowered, the gripped ring by a movement of the slide 7 0 can be brought outside of the assembly formed by the rotary disk 21, the lower mould carriers and the lower mould parts to be deposited on a suitable conveyor outside the chamber 20 or to be transported to a working station.

Each of the mould carriers on the rotary disk 21 is enclosed by a cylindrical shell; two of said shells are shown in the drawing and designated 91 and 91'. These shells are arranged and designed in the same manner, and the following description of one shell 91 therefore applies also to the other. The shell 91 is carried by uprights 92 and brackets 93 on the rotary disk 21. On its inner side the shell has a circular cooling medium conduit 94. Along said conduit there is provided a number of openings 95 which are directed radially towards the joint between the mould parts 40 and 47 when the mould is closed. The conduit 94 is connected to a supply line, preferably for air under pressure, in a manner not shown. When the lower mould part 40 is closed against the upper mould part 47 cooling medium can be supplied in the manner indicated, preferably after the beginning of the casting operation, to the joint between the two mould parts for cooling of the mould and then, after the casting has obtained sufficient strength so that absolutely no melt is thrown out of the mould, for a controlled cooling of the casting in that the mould parts 40 and 47 are slightly separated while cooling medium is blown through the joint between the mould parts towards the casting. For the rest the mould parts may be bevelled at the outer edges of their facing surfaces, as is shown at 96 and 97, in order that the cooling medium supplied may be pressed in better between the mould parts. After the mould parts 40 and 47 have been further separated cooling medium can still be supplied to the cast article lying in the lower mould part.

The apparatus shown in FIGS. 5 and 6 is adapted for casting segmental or circular castings. This embodiment of the invention includes a rotary tubular shaft on which there is arranged a pair of diametrically opposed support arms 126 and 126' which are axially movable on the shaft 125 by means of a pair of hydraulic cylinders 127 which are disposed each between one abutment 128 secured to the shaft 125 and the corresponding support arm. The support arm 126 carries a mould carrier 134) rotatably mounted by means of ball bearings 129, and a lower mould part 131 mounted on said mould carrier. The other support arm 126' is arranged in a corresponding manner so that the mould parts carried by the support arms can be caused to change places in the same way as was described in connection with the preceding embodiment, for which reason it will not be described in more detail here. The lower mould part 131 is closed against an upper mould part 132 carried by an upper mould carrier 133 which is rotatably mounted on a stationary bushing 134 in the manner earlier described and is driven 7 by means of a belt 135 and braked by means of a brake belt'136. The two mould parts 131 and 132 can be pressed against each otheralon'g a separating line 137 by means of the cylinders 127.- A supply pipe 138likewise in a manner earlier described-4s rotatably mounted in the bushing 134 and in the uppermould carrier 133 and is driven by a belt'139. This supply'pipe' 138 divides itself into two mouth portions 140a and-140b situated at the same level and directed radially outwards from the supply pipe, whereby their mouths, in the closed position of the mould parts, lie inside the mould cavity formed by the mould parts. The supply pipe'138 is rotatable not only by means of the belt139 but also by means'of the upper mould carrier 133, which is provided witha pivotally mounted spring loadedpawl 1'41which' engages'one carried along by the mouldcarrier' 133 driven by the belt 135, and the resultant rotary movement of the mould carrier 133 is assumed to take place, in the embodiment shown, in a clockwise direction as seen in FIG. 6. In the interior of the mouldcavity there are arranged on the inner side 'of'the wall of the lower mould part 131 a pair of diametrically opposed rib-shaped

projections

143a and 143b which extend over the entire axial length of said wall. The notches 142aand 14% are so arranged relative to said rib-shaped projections'143a and 1431) that the mouths of the two branches 140a and 140b, when the pawl 141 engages in one of said notches, are positioned at one of the projections 143a and 1431; in order that the pouring of the melt into the mould-shall start at one projection and be terminated'at the other projection.

At the use of this apparatus the mould is first closed and then the upper mould carrier 133 and the upper mould part 132 carried thereby are caused to rotate by means of the belt 135, the lower mould part 131 and the lower mould carrier- 130 being carried along in the rotation by the frictional engagement between the mould parts along .the separating line 137 while the supply pipe 138 is carried along in the rotation by means of the pawl 141 which is in engagement with one of the notches 142a and 142i).

After the suitable number of revolutions has been reached for the mould and the supply pipe 138 the latter is given a slightly higher speed than the mould at the moment when the melt flows into the mould in that said pipe is rotated by means of the belt 139 so, that the mouths of the branches 140a and 14% move along an arc of a circle between the two

projections

143a and 143b, whereby a semi-circular arc profile'or a semi-circular mouldingis cast between the two projections 143a and 14311 on either side thereof. It is obvious that a relative movement between the mould and the supply pipe can be realized in a manner. other than that shown here and that this relative movement can be produced by increasing or reducing the speed of rotation of the mould or the supply pipe.

The embodiment according to FIGS. 5 and 6 can be modified for the casting of two rings. In such a case two annular cavities, one above the other, are arranged in the lower mould part 131 and in accordance therewith the mouth portio'ns14ila and 14 3b are disposed at dilferent levels so that the material to be cast can'fiow' into each of the two annular cavities. The apparatus is used in the same manner as the apparatus according to FIGS. 3 and 4, but two rings are cast at the same time The apparatus according to FIGS. 7 and 8 includes an upper mould carrier 156 which is rotatably'mounted on a stationary bushing 155 and carries an upper mould part 157. Adapted for cooperation with this upper mould part is an intermediate mould part 158 which is rotatably mounted in a water film produced in a jacket 159. Said jacket is carried by a rotary disk 160 which is disposed on a tubular shaft 161 and is axially movable. rotary disk carries a number of furtherinterrnediate mould parts which are identical with the intermediate mould part The B 153'and one of which is shown at 158. The apparatus further includes a lower mould part 162 which is attached to a mould carrier 162 which is mounted for rotation in a support arm 164 by means of ball bearings 163. The support arm 164' is integral with a sleeve 165 which is axially movable but non-rotatable on thetubular shaft 161, whereas the rotary disk is fixedly attached to the tubular shaft 161 and mounted for rotation. To raise and lower the unit formed by the support arm 164and the sleeve a pair of hydraulic cylinders 167" is arranged between said unit and a stationary abutment 166. A core 168 is movable in the interior of the lower mould part 162 in such a way that in the operative position of the apparatus it extends with its upper end into the cavity formed by the mould parts, but is withdrawable from said cavity by axial displacement. A hydraulic cylinder 169 is adapted to displace the core 168. This cylinder is carried by a member 176 extending from and integral with the sleeve 165. The core 168 is mounted for rotation on the piston rod 172 of the hydraulic cylinder 169 by means of ball bearings 171. It is hollow and an' axially disposed pipe 173 for supplying cooling medium to the interior of the core projects into the hollow thereof. The different mould parts can be rotated and braked in analogy to what has been described earlier. The core 168 is coupled to the lower mould part 162 by means of a wedge 168 which permits the core to' be axially displaced relative to the lower mould part.

The embodiment in FIGS; 7 and 8 also exemplifies the use of loose inserts in the mould, which may present cooling apertures. Such an insert, for instance a silicate insert, is located in the upper portion of the intermediate mould part 158 at 174. This insert has a supply passage 176 connected to the supply pipe 175 of the mould. Such inserts may of course be used in different designs and in different Ways and may consist of different materials. In connection with this embodiment it should also be mentioned that the inserts may consist of a number of lamellar elements which are provided with mould cavities at their periphery and are withdrawable fromthe mould cavity for instance also in the course of the casting operation.

The embodiments described above and shown in the drawing may of course be modified according to the object contemplated, and the structural details shown here may of course easily be assembled to other combinations than those shown here. Therefore, the invention is not limited to what is shown in the drawings and described in the specification but covers all conceivable modifica-' tions within the spirit and scope of the appended claims.

What I claim is:

1. A method of centrifugal casting of rings having round or polygonal'profiles with rounded outer edges, comprising bringing together the parts of a multi-part mold having at least an upper part and a lower part and being rotatable in a horizontal plane, casting a ring in the mold by inserting a supply pipe into the mold, rotating the mold, rotating the supply pipe in synchronism with one point on the mold until the time at which the molten metal starts to flow through the supply pipe into the mold, flowing molten metal through the supply pipe into the mold, rotating the pipe relative to the mold during the flow of molten metal into the mold until the molten metal has flowed into all of the parts o f the circumference of the mold, and after the casting has solidified sufiiciently, separating the mold parts, carryiug away the casting in the lower mold part which serves as a support, and moving a further mold part identical with that carried away together with the remaining upper mold part to complete a further mold ready for casting a new article, and cooling the casting previously cast in the carried-away mold part and withdrawing the cooled casting from said carried-away mold part.

2. A method as claimed in claim 1 in which the molten metal is discharged from the pipe in the direction opposite to the direction in which the pipe is rotated, whereby the molten metal is relatively gently deposited in the mold while the mold and the supply pipe are rotating at relatively rapid speeds.

3. A method as claimed in claim 1 in which the molten metal is discharged from the pipe in a direction circumferentially of the mold, and the mold and the supply pipe are driven at angular speeds which differ from each other only slightly, whereby the molten metal leaving the supply pipe will have a speed approximately zero with respect to the mold.

4. A method as claimed in claim 1 further comprising the step of placing a covering material over the molten metal in the mold immediately after flow of the molten metal into the mold has ended.

5. An apparatus for centrifugal casting of rings having round or polygonal profiles with rounded outer edges, comprising a plurality of lower mold parts each of which is identical with the other lower mold parts, a carrying device rotatable about a vertical axis and on which said lower mold parts are rotatably mounted at intervals around said carrying device for rotation about vertical axes, an upper mold part rotatably mounted for rotation around a vertical axis and positioned above one of the lower mold parts on said carrying device and beneath which the other lower mold'parts are moved when said carrying device is rotated, raising means on said carrying device for raising said lower mold parts into engagement with said upper mold part to form a complete mold, mold rotating means connected to said mold parts for rotating them about their vertical axes, a supply pipe extending through the upper mold part along the vertical axis thereof and mounted for rotation about said vertical axis, said supply pipe extending into the mold formed by the upper mold part and a lower mold part and laterally of said axis to a point adjacent the periphery of said mold, and supply pipe drive means connected to said supply pipe for rotating said supply pipe about said 3X15.

6. An apparatus as claimed in claim 5 in which the end of said supply pipe with in the mold extends parallel to the direction of movement of the end of the pipe and opens in the direction opposite to the direction of rotation of the pipe.

7. An apparatus as claimed in claim 5 and pawl means coupling said upper mold part and said supply pipe for driving said supply pipe at a speed equal to the speed of the upper mold part, whereby the supply pipe is driven at the same speed as the mold, and when pouring of the molten metal into the mold is started, the supply pipe can be dniven at a greater speed than the speed of the mold.

8. An apparatus as claimed in claim 5 further comprising a continuous closed metal supply system adapted to extend from a means for holding molten metal and connected to said supply pipe for keeping the molten metal out of contact with the atmosphere.

9. An apparatus as claimed in claim 8 in which said apparatus has a sealing means around the end of said supply pipe adapted to be sealed to a means for holding molten metal, said apparatus having a gas inlet through said sealing means for admitting a protective gas into said supply pipe for protecting the molten metal from the atmosphere.

10. An apparatus as claimed in claim 5 and a protective gas supply pipe attached to the said molten metal supply pipe within the mold having an outlet end extending laterally of the mold to a point adjacent the periphery of the mold, the inlet end of the said protective gas supply pipe extending through the lower mold part along the vertical axis of rotation thereof, and a protective gas supply coupled to the lower end of said protective gas supply pipe.

11. An apparatus as claimed in claim 10 in which said protective gas supply pipe is in two parts, an upper part secured to said molten metal supply pipe and a lower part extending through each lower mold part, said upper and lower pipe parts engaging with each other when a lower mold part is moved into engagement with said upper mold part.

12. A method of centrifugal casting of rings having round or polygonal profiles with rounded outer edges, comprising bringing together the parts of a multi-part mold having at least an upper part and a lower part and being rotatable in a horizontal plane, casting the ring in the mold and rotating the mold during casting, while casting and rotating the mold, protecting the molten material from the atmosphere by supplying protective gas to the interior of the mold and directly against the cast material immediately after it has been poured into the mold, and after the casting has solidified sufficiently, separating the mold parts, carrying away the casting in the lower mold part which serves as a support, and moving a further mold part identical with that carried away together with the remaining upper mold part to complete a further mold ready for casting a new article, and cooling the casting previously cast in the carried-away mold part and withdrawing the cooled casting from said carried-away mold part.

References Cited by the Examiner UNITED STATES PATENTS Re. 24,827 5/60 Lasater et a1 2265 1,634,914 7/27 Reichold 2265 X 1,721,115 7/29 Harrington 2277 1,885,465 11/32 Moulton 2277 1,908,607 5/ 33 Hokin 2265 2,023,040 12/35 Adams 2265 2,570,325 10/51 Dalton 2265 2,681,485 6/54 Smith 22215 2,829,408 4/58 Shuck 2265 2,966,709 1/ 61 Ruppel et a1 2277 X MICHAEL V. BRINDISI, Primary Examiner.

MARCUS U. LYONS, WINSTON A. DOUGLASS,

Examiners.

Claims

5. AN APPARATUS FOR CENTRIUGAL CASTING OF RINGS HAVING ROUND OR POLYGONAL PROFILES WITH ROUNDED OUTER EDGES, COMPRISING A PLURLAITY OF LOWER MOLD PARTS EACH OF WHICH IS INDENTICAL WITH THE OTHER LOWER MOLD PARTS, A CARRYING DEVICE ROTATABLE ABOUT A VERTICAL AXIS AND AN WHICH SAID LOWER MOLD PARTS ARE ROTATABLY MOUNTED AT INTERVALS AROUND SAID CARRYING DEVICE FOR ROTATION ABOUT VERTICAL AXES, AN UPPER MOLD PART ROTATABLY MOUNTED FOR ROTATION AROUND A VERTICAL AXIS AND POSITONED ABOVE ONE OF THE LOWER MOLD PARTS ON SAID CARRYING DEVICE AND BENEATH WHICH THE OTHER LOWER MOLD PARTS ARE MOVED WHEN SAID CARRYING DEVICE IS ROTATED, RAISING MEANS ON SAID CARRYING DEVICE FOR RAISING SAID LOWER MOLD PARTS INTO ENGAGEMENT WITH SAID UPPER MOLD PART OT FORM A COMPLETE MOLD, MOLD ROTATING MEANS CONNECTED TO SAID MOLD PARTS FOR ROTATING THEM ABOUT THEIR VERTICAL AXES, A SUPPLY PIPE EXTENDING THROUGH THE UPPER MOLD PART ALONG THE VERTICAL AXIS THEREOF AND MOUNTED FOR ROTATION ABOUT SAID VERTICAL AXIS, SAID SUPPLY PIPE EXTENDING INTO THE MOLD FORMED BY THE UPPER MOLD PART AND A LOWER MOLD PART AND LATERALLY OF SAID AXIS TO A POINT ADJACENT THE PERIPHERY OF SAID MOLD, AND SUPPLY PIPE DRIVE MEANS CONNECTED TO SAID SUPPLY PIPE FOR ROTATING SAID SUPPLY PIPE ABOUT SAID AXIS.