US3651859A

US3651859A - Apparatus for centrifugal casting of tubular objects

Info

Publication number: US3651859A
Application number: US826039*A
Authority: US
Inventors: Hans Heinz Wahl; Alfons Gumiaskl; Gunther Lohmann
Original assignee: Luitpoldhuette AG
Current assignee: Luitpoldhuette AG
Priority date: 1968-03-22
Filing date: 1969-03-21
Publication date: 1972-03-28
Anticipated expiration: 1989-03-28
Also published as: JPS4813212B1; FR2004528A1; DE1758026A1; GB1206077A; DE1758026B2

Abstract

In a conventional de Levaud centrifugal pipe casting machine which includes a rotatable water casing, a mold within the casing and rotatable therewith, cooling water supply and discharge system, ball bearings rotatably supporting the water casing, sealing glands, and means through which rotation of the water casing is effected, the improvement comprising casing sleeves mounted exteriorly at each end of the water casing which support casting machine parts such as cooling water supply and discharge system, ball bearings, sealing glands, etc., and are detachably secured to the water casing for rotation. When it is desired to remove the water casing from the casting machine, the casing sleeves are detached and moved apart to present the water casing free of the auxiliary machine parts.

Description

United States Patent Wahlet al.

[451 Mar. 28, 1972 [54] APPARATUS FOR CENTRIFUGAL CASTING OF TUBULAR OBJECTS Luitpoldhutte Aktiengesellschaft, Amberg, Germany [22] Filed: Mar.21,1969

[21] App]. No.: 826,039

[73] Assignee:

[30 l' oreign Application Priority Data Mar. 22, 1968 Germany ..P 17 58 026.6

[52] US. Cl ..l64/29l, 164/297, 164/298 [51] Int. Cl ..B22d 13/10 [58] Field oiSearch ..l64/84,114,115,l16,117, 164/118, 175, 286, 287, 288, 291, 292, 293, 294,

2,252,219 8/1941 Trotzke ..164/291 2,461,765 2/1949 Olt ..l64/l 14 X 2,500,799 3/1950 Carrington.. ..164/291 2,681,485 6/1954 Smith ..l64/114 X FOREIGN PATENTS OR APPLICATIONS 995,992 12/1951 France 164/297 Germany Great Britain 164/1 14 Primary Examiner--Robert D. Baldwin Assistant Examiner-John E. Roethel Attorney-Hammond & Littell [57] ABSTRACT In a conventional de Levaud centrifugal pipe casting machine which includes a rotatable water casing, a mold within the casing and rotatable therewith, cooling water supply and discharge system, ball bearings rotatably supporting the water casing, sealing glands, and means through which rotation of the water casing is effected, the improvement comprising casing sleeves mounted exteriorly at each end of the water casing which support casting machine parts such as cooling water supply and discharge system, ball bearings, sealing glands, etc., and are detachably secured to the water casing for rotation. When it is desired to remove the water casing from the casting machine, the casing sleeves are detached and moved apart to present the water casing free of the auxiliary machine parts.

4 Claims, 5 Drawing Figures PATENTED MR 2 8 I972 SHEU 1 UF 3 ATTORNE S PATENEnmzs m2 SHEET 3 BF 3 3 Q3 3 xv ATTORNEYS APPARATUS FOR CENTRIFUGAL CASTING OF TUBULAR OBJECTS PRIOR ART The de Levaud process of casting pipe in permanent metal molds has been extensively practiced for many years. Present processes, in which the metal temperature is particularly critical and must be maintained within a very narrow range, comprise the use of cylindrical metal molds disposed within a water jacket and adapted to be rotated at suitable speeds. Rollers are mounted circumferentially of the water jacket at spaced intervals thereof to facilitate rotation. The water jacket is mounted on wheels so that the entire assembly can be moved by means of a hydraulic cylinder in the direction of the longitudinal axis of the mold. This movement is along a fixed bed inclined slightly from the horizontal. The molten metal is fed into the mold through a similarly inclined trough which is mounted at the upper end of the fixed bed and extends like a cantilever beam almost the full length of the mold when the mold is at the extreme upper position. When the mold is in this position, it is ready for casting. After the casting machine ladle has been filled, the machine operator brings the mold up to speed and actuates the mechanism controlling the tilting of the ladle. In a few seconds, the iron has filled the bell space, at which time, the operator starts the mold carriage longitudinally down the inclined bed. The stream of iron discharged from the trough is distributed along the surface of the mold where it is held in place by centrifugal force and forms the pipe upon cooling. After the metal has solidified, mold rotation is stopped and the pipe is extracted from the mold by moving mold carriage longitudinally up the inclined bed while holding the pipe stationary. The mold carriage is then moved back down the inclined bed to place the mold in a convenient position for setting the bell core, and if a mold coating is used, it may be applied during this stroke of the machine. The bell core is then set and the mold carriage moved to the extreme upper end of the inclined bed to begin another casting cycle.

The distribution of the metal along the mold length during the casting operation is controlled by the operator who must commence movement of the mold assembly away from the trough at the correct moment or else the metal delivered to the bell end will not give the proper bell end thickness. For instance, if the carriage movement is started to soon the bell end will be too thin, and if it started late the bell end will be thick. Since it is usually impractical to place the machine operator in a position which commands a good view of the bell end of the mold, it is usually necessary to have a bell core setter, who is in a position which affords the best view of the bell end of the mold, signal the operator to start the mold carriage retraction away from the trough. This is called flagging and is accomplished by throwing a switch which turns on a light or other suitable signal on the operators panel.

In addition to starting the mold retraction at the proper instant, the operator must also judge the proper position in which to stop the mold carriage momentarily while the spigot end of the pipe is being cast, following which, retraction of the mold carriage is completed and the ladle pouring is terminated. This is known as hand-checking and is necessary to build up the proper metal thickness at the spigot end of the mold. It is apparent that it is completely within the control of the operator who determines both the position and the duration of the stop. When the mold movement is stopped in the wrong position or for too short a time, the spigot end is made thin, and if it is stopped for too long a time, the spigot end is cast thick.

Semi-automatic controls to control flagging, hand-checking and ladle cut-back have been provided on the centrifugal pipe casting machines replacing human judgement and thereby obtaining a pipe of more uniform thickness.

In the course of development in the art of centrifugal casting machines, it was customary to support the water casing by means of at least two groups of two to three rollers distributed along a partial circumference of the water casing. The rotation of the water casing in such an arrangement was strained and non-uniform resulting in accelerated wear of rollers. Additional means was generally provided in the form of counterrollers to bufi'er axial forces. Needless to say, unsteady rotation of the water casing, and the mold within, unfavorably influenced the quality of pipes produced thereby.

To improve the situation, it was proposed to use ball bearings for rotatably supporting the water casing. These ball hearings were arranged around the full circumference of the water casing and indeed provided a smoother and much more efficient rotation in terms of the higher quality of pipe produced.

Although the ball bearings, arranged as described above, did resolve one problem, they spawned a number of new ones. When it was desired to remove the water casing from the casting machine, the ball bearings had to be removed which required a considerable amount of time and resulted in long periods of idleness of the casting machine. Multiplying this time by the number of casting machines in the plant gives an indication of amount of time that was unnecessarily wasted. Furthermore, when the water casing was removed from a casting machine, it was necessary to have an extra set of ball bearings on hand for another water casing which was to be installed in the casting machine. The necessity for providing additional set of ball bearings every time a different water casing was installed increased investment costs which directly affected the cost of the pipes produced. It should be now apparent to one that, in addition to the multitudinous overhead and production costs, the cost of the pipes was further inflated by the cost of replacement sets of ball bearings and by inefficient utilization of the casting machines.

OBJECTS OF THE INVENTION It is an object of this invention to obviate disadvantages of the prior art centrifugal casting machines by reducing machine shut-down time and investment cost.

It is another object of this invention to provide a centrifugal metal casting machine whereby the time for changing water casing, together with the mold is substantially reduced.

It is still another object of this invention to provide a centrifugal metal pipe casting machine which incorporates a design feature allowing for thermal expansion and contraction.

A further object of this invention is to provide a pipe casting machine which would allow for remaining the auxiliary parts mounted on the casing sleeves while replacing the water casing.

THE INVENTION The present invention relates to a centrifugal pipe casting machine which comprises a water casing and an integral mold disposed therein, rotatably mounted on carriage provided with wheels and serving as a conveying means for the mold assembly. Rotary movement to the water casing and the mold may be imparted by an electric motor mounted on the frame of the machine and operatively connected to the water casing through suitable gearing or belt-drive and through casing sleeves exteriorly mounted at the extremities of the water casing. The wheels of the carriage are arranged to travel on rails fixed to an inclined base of the casting apparatus. A piston operating in a cylinder secured to the base has its outer end connected to the carriage for moving the carriage to and from on the rails during the casting operation.

A pouring trough, of a well-known type is fixed at its inlet by means of support which is rigidly mounted with respect to the base so that the outlet end may move in and out of the mold as the mold carriage is moved back and forth on its tracks. Molten metal is supplied to the pouring trough through a spout curving downwardly from the outlet of a ladle. Titlting of the ladle is effected by means of a piston-cylinder arrangement about trunnions affixed to the ladle.

The novel aspect of this invention resides in the provision of a supporting casing sleeve on the end portions of the water casing. The casing sleeves are detachably secured to the water casing and rotate therewith during the casting operations. Auxiliary parts of the casting machine, such as cooling water supply and discharge system, ball bearings, sealing glands and various other attachments which are nonnally mounted on the water casing are, in accordance with the present invention, mounted on the casing sleeves. Each casing sleeve is rotatably secured to and supported by a separate sled which is attached to an intermediate carriage platform of a carriage by means of a piston reciprocating in a double-acting cylinder. This piston is rigidly secured to the sled and slidably communicates with the double-acting cylinder disposed within the intermediate carriage platform. When it is desired to replace the water casing, a support means is provided for the water casing. The water casing is detached from the casing sleeves at both ends thereof and the pistons are actuated to disengage the casing sleeves from the water casing, leaving a detached water casing resting on the support means. The water casing can subsequently be removed to any desired location by means of a crane.

In the accompanying drawings, which illustrate the preferred embodiment of the invention,

FIG. 1. is a cross-sectional view of the water casing.

FIG. 2. is a cross sectional view of the pair of easing sleeves.

FIG. 3. is a cross-sectional view through the bell end of the centrifugal pipe casting machine.

FIG. 4. is a cross-sectional view through the spigot end of the pipe casting machine.

FIG. 5. is a view of the sled taken through plane of FIG. 3.

Referring to the drawings, the water casing 10, separately illustrated in FIG. 1, has a plurality of circumferentially arranged lugs l2, 14 on its periphery. As shown in FIGS. 3 and 4, mold 20 is positioned within water casing and is spaced therefrom by adjustable spacers 22 which project from the water casing into the cooling water chamber. The mold illustrated in the drawings is integral at its end with the water casing, as is apparent from FIG. 3.

The casing sleeves 16, 18 are journaled over the end portions of water casing 10, and are secured thereto by means of bolts 24 projecting through lugs l2, l4 and into

bores

26, 28 provided in the bell end and spigot end of the casing sleeves, respectively. Cooling water supply and discharge assembly, generally designated by numeral 30, is supported by the respective casing sleeves and is in communication with by the water casing 10 through conduit 34. Rotation of the water casing 10, together with the casing sleeves l6, 18, is facilitated by ball bearings 36 mounted around the circumference of the casing sleeves and disposed in supporting relationship. O-rings 38 and sealing glands 40 provide' for sealing between cooperating parts. Rotation of the water casing, casing sleeves and the mold is effected by an electric motor suitably mounted on the frame of the casting machine through what may be a V- belt operatively engaging a drive-gear 42 on the casing sleeve 16. Rotation of the mold assembly may also be effected by any other suitable means, such as cooperating set of gears.

The mold assembly is supported at each end on carriage 44 by structural elements forming chamber 46 and cylindrical support block 48. As is evident from FIGS. 3 and 4, the cylindrical support block 48 also forms a supporting surface for ball bearings 36. Carriage 44 consists of

sleds

50, 52 and an intermediate carriage flatform 54. Sled 52 is detachably secured to the intermediate carriage platform 54 by a pair of cooperating lugs 56, 58 situated on the sled and the intermediate carriage platform, slotted bolt 60, and wedge 62 driven into the slot.

Interaction between the intermediate carriage platform 54 and the sleds is further enhanced by a stem 64 which extends longitudinally from each sled, and a piston 66 attached to the stern and disposed for reciprocating movement in a doubleacting cylinder 68 provided at each end of the intermediate carriage platform 54.

Each piston 66 can be independently acuated, in a manner well known in the art, to impart relative movement between each sled and the intermediate carriage platform 54. A plurality of swingable supports 70 are disposed on the carriage 44 along the extent of the water casing to provide additional support thereto. These supports are swung out whenever it is desired to remove the water casing. The carriage is supported on

wheels

72, 74 which ride on tracks disposed on an inclined surface.

In operative relationship, sled 50, is firmly linked with the intermediate carriage platform 54 by aligned lugs 56, 58, bolt 60 and wedge 62 driven into the slot in said bolt 60. Sled 52 can be shifted relatively to the platform 54 for compensation of thermal expansions and contractions. Supports 70 are swung to their operative position and maintain water casing in the horizontical plane, relative to the inclination of the machine bed. The mold assembly is rotated by a V-belt driven by an electric motor and engaged to the mold assembly through drive-gear 42. Casing sleeves l6, 18 are rigidly secured to water casing 10 by bolts 24 and rotate therewith in unison.

Due to special design features of the casting apparatus described above, expansion and contraction of the machine parts due to thermal cycle of the centrifugal casting process are easily compensated thereby. This feature of the apparatus is shown in the drawings as exterior frusto-

conical surfaces

76, 78 on water casing 10 and mating interior surfaces 80, 82 on respective casing sleeves l6, 18. When axial thermal expansions and contractions are induced, they are compensated by relative movement of sled 52.

When it is desired to replace water casing 10 together with mold 20, the casing sleeves 16, 18 are disconnected from water casing 10 by extracting bolts 24, and sled 50, is disconnected from intermediate carriage portion 54 by removing wedge 62 and bolt 60. A crane is moved over the water casing and cables are draped around the water casing. Supports 70 are swung out from under the water casing and the double-acting cylinders 68 are actuated to cause movement of the sleds away from the intermediate carriage platform 54. Since the casing sleeves 16, 18 are rotatably secured to respective sleds '50, 52, outward movement of the sleds will eventually clear casing sleeves 16, 18 from water casing 10, leaving the water casing suspended by the crane cables. Thereafter, the water casing is moved by crane to any desired location. To re-assemble the casing apparatus, another water casing is installed by positioning it between the casing sleeves, actuating the double-acting cylinders to move the sleds inwardly until the water casing is snugly nestled within opposing casing sleeves. The reassembly procedure is completed by securely fastening the casing sleeves to the water casing, and the sleds to the intermediate carriage platform.

Various modifications of the centrifugal pipe casting apparatus described herein may be made without departing from the spirit of scope thereof. It is to be understood that their invention is to be limited only as defined by the appended claims.

We claim:

1. A centrifugal pipe casting apparatus comprising a water casing provided with casing sleeves journaled on its ends mounted for rotation, a mold disposed in said water casing in spaced relationship and rotatable therewith in unison, means for detachably securing said casing sleeves to the water casing for rotation, auxiliary casting parts mounted on said casing sleeves, moveable support means for said sleeves comprised of an intermediate carriage platform and a detachable sled on each end of said platform, means for rotatably affixing said sleeves to said sleds and means for imparting relative movement between each sled and the intermediate carriage platform whereby the casing and mold can be separated from the rest of the apparatus without disassembly thereof.

2. The apparatus of claim 1 wherein the means for imparting relative movement between the sleds and the intermediate carriage platform is a double-acting piston cylinder arrangement.

6 3. The apparatus of claim 2 wherein a piston is attached to 4. The apparatus of claim 1 wherein each end of the water each of said sleds and a cylinder is disposed at each end of said casing 11 u mfial xt rior urface and each casing platform whereby a piston of one sled is operatively disposed Sleeve has 3 mating ifltel'ior surface assure axial alignment is one of said cylinders and the other piston is operatively ofthe Sleeves and casmg' disposed in the second cylinder.

Claims

3. The apparatus of claim 2 wherein a piston is attached to each of said sleds and a cylinder is disposed at each end of said platform whereby a piston of one sled is operatively disposed is one of said cylinders and the other piston is operatively disposed in the second cylinder.

4. The apparatus of claim 1 wherein each end of the water casing has a frusto-conical exterior surface and each casing sleeve has a mating interior surface to assure axial alignment of the sleeves and casing.