US2901793A

US2901793A - Centrifugal pipe casting machine

Info

Publication number: US2901793A
Application number: US674748A
Authority: US
Inventors: Ralph W Kurtz
Original assignee: JAMES B CLOW AND SONS Inc
Current assignee: JAMES B CLOW AND SONS Inc
Priority date: 1957-07-29
Filing date: 1957-07-29
Publication date: 1959-09-01
Anticipated expiration: 1976-09-01

Description

Sept. 1, 1959 R. w. KURTZ CENTRIFUGAL PIPE CASTING MACHINE Filed July 29, .1957

3 Sheets-Sheet -1 Sept. 1, 1959 R. w. KURTZ 2,901,793

CENTRIFUGAL PIPE CASTING MACHINE Filed July 29, 1957 5 Sheets-Sheet 2 /Z J9 O l O 59 68 66 9a 9 I v I J7 Sept. 1, 1959 R. w. KURTZ CENTRIFUGAL PIPE CASTING MACHINE Filed July 29, 1957 3 Sheets-Sheet 3 2,901,193 1C6 Patented Sept. 1, 1959 CENTRIFUGAL PIPE CASTING MACHINE Ralph W. Kurtz, Coshocton, Ohio, assignor to James B. Clow & Sons, Inc., Coshocton, Ohio, a corporation of Delaware Application July 29, 1957, Serial No. 674,748 7 Claims. (CI. 22-65) This invention relates to the casting of tubular products; particularly to the casting of iron pipes, centrifugally, in tubular steel molds.

These molds, for the most part, have a length several times as great as their diameter. Their strength as beams is not so great but what they tend to warp slightly in service, unless constrained, and form portions of the pipe eccentrically.

Molds for pipes having a nominal diameter less than about five inches can be reinforced very well by a surrounding sleeve, such as that described in this applicants Patent No. 2,586,349. A better scheme for mounting larger molds is revealed herein, a scheme that employs relatively convenient and powerful equipment.

In lieu of a sleeve, rollers are used to both support and steady the mold. Warpage of the mold is resisted by air cylinders, remotely controlled and applicable to whatever extent is needed. The rollers are mounted on axles which are supported in the machine housing without the aid of bolts. Grease is sealed in the rollers by long-wearing plastic rings. The mold is retained axially by a collar clamped thereto and lubricated automatically, by water.

In the accompanying drawings:

Figure 1 is a side elevational view, partly exploded, of a casting machine that embodies a preferred form of this invention;

Figure 2 is a transverse sectional view taken along the line 2-2 of Figure 1 (a similar view is had at two locations);

Figure 3 is a side sectional view of one of the rollers; and Figure 4 is a fragmentary sectional view of the rotor taken along the line 4-4 of Figure 2.

Not shown, but well known in this art, is equipment used to pour molten metal into the mold; and, tackle employed to extract the cast product. Depicted is the centrifugating unit only, an apparatus constituted by three principal sub-assemblies; a rotor equipped with sealing girts, a lower box-half 50 supporting the rotor, and an upper box-half 90 supporting a motor.

An annular chamber 11, defined. by the box-halves 50, 9t) and the begirted rotor, is filled with hot water under pressure when casting pipes. All parts within the chamber are subjected to a washing and corrosive action. Also, and since it is sometimes necessary or expedient to jar the cast product loose from the mold, the parts must be constructed in a more rugged manner than would otherwise be necessary.

As best shownin'Figure 4, the rotor 10 comprises a tubular mold 12 and various appurtenances. A sealing collar 13 has packed engagement with the axially inner side of a shoulder 14 projecting radially outwardly from an enlarged, or bell, end of the mold. A series of screws 15 serves to clamp the shoulder 14 tightly between the collar 13 and a core frame 16 mounted in an annular niche defined by the shoulder and the collar.

Two or more latches 17 are employed to hold a reinforced sand core such as 18 in the frame 16.

A flared packing 21 blocks an annular gap between a batten 23 and a journal 22 of the collar. A series of bolts 24 holds the brim of the packing 21 tightly between the batten 23 and a girt 25. Axially outwardly from the batten 23 a distance varying with the temperature of the mold, a gear 26 is rigidly secured to the collar. Extending radially inwardly from the collar, a series of vanes 27 forces water therefrom when the mold is inundated and rotated.

A sealing hood 29 has axially packed relationship with the plain, or spigot, end of the mold 12. A split collar 30, comprising two semi-circular halves, is radially supported by the hood 29 and abuttingly engaged by a shoulder 31 of the mold. A series of screws 32, projecting axially from the hood, holds the collar 30 tightly against the shoulder 31. Mounted in an annular niche, defined by the hood 29 and an inwardly projecting rim of the collar 30, is a thrust bearing 33 which has sliding engagement with a hard race 34 rigidly secured to a buttress or portal 35. A circular series of

ports

36 and 37, provided in the hood 29 and collar 30 respectively, force water therethrough when revolved therein.

A flared packing 39, smaller than the flared packing 21, blocks an annular gap between a batten 40 and a journal 41 of the hood. The batten 40 cooperates with a series of screws 42 in holding the brim of the packing 39 tightly against the axially outer face of a girt 43. A curbing 44, secured to the opposite face of the girt by screws 42, has axially adjacent relationship with a flange 45 rigidly mounted on the hood 29. Protruding from the spigot end of the mold 12 is a flared ring 46 which has radially supportive engagement with the hood 29 and is secured thereto by a series of screws 47.

As indicated by dashed lines (Figure 4), the box-halves 50, have radially packed and axially abutting relationship with the

girts

25, 43 and the portal 35. As shown in Figures 1 and 2, the box-half 50 is provided with projections 51, to resist the thrust of the box-half 90; and, various other structural featurespockets 52, struts 53, and bosses 54to accommodate four rows of rollers 55 in radial engagement with the mold 12.

The rows are disposed about equally distant from imaginary planes passed vertically and horizontally through the axis of the mold. Each of the rollers is mounted with another roller on the opposite ends of an axle (one in Figure l is shown fragmentarily). The upper rollers 55 are mounted on axles 57 which comprise saddles 58 and arms 59. The lower rollers 55 are mounted on axles 60 similar to axles 57 but having no arms 59 and, instead of saddles 58, stands 61. All of the

axles

57, 60 are provided with yokes or thrust arms 63 which project radially outwardly therefrom and have axially abutting relationship with the pockets 52 of the box-half 50. The stands 61 are supported by the struts, or slides, 53 and restricted laterally outwardly by Wedges 64 mounted on brackets 65. Screws 66 serve to adjust the wedges 64; screws 67, to hold the brackets 65 tightly on the bosses 54. Arms 59 link the upper axles 57 with pins 68 mounted parallel thereto on the brackets 65.

As brought out in Figure 3, each of the rollers 55 comprises a self-aligning roller bearing 70, a metallic tire 71 mounted on the bearing, a cap 72 disposed in radially packed relationship with the tire, and a series of screws 73 which hold the outer race of the bearing tightly between the cap and a shoulder 74 of the tire.

Each end of the

axles

57, 60 is provided with a journal 76 and a smaller journal 77 extending outwardly therefrom. A stand 61, or saddle 58, is mounted on the journal 76 in axially abutting relationship with a spacer 78 mounted on the journal 77'. The inner race of the roller bearing 70 is held between the spacer 78- and a nut 79 threaded on the end of the axle. A sealing ring 80 is pressed against the shoulder 74 of the roller tire by springs 81 supported by the stand- 61, orsaddle 58. An annular packing 75, mounted on the spacer 78, serves to support the sealing ring 80 in a semi-floating manner.

The bearing 70 is thus confined in a chamber 8} defined by the tire 71, the cap 72, the journal 77, the spacer 78 and the ring 80. Grease is introduced to this chamber 82, via a duct 83 which extends entirely through the axle and communicates with piping 84 (Figure Screens 85, mounted in the ends of the duct 83, serve to keep chips from entering the bearing 70 and to equalize the pressure of the grease distributed by the duct,

Rounding out the lowerbox-half equipment buthaving no influence on the character of this invention, are track wheels 86', a draw bar 87, and the lower section of a guard 88. All air, water and electric supply lines are connected with the upper box-half 90; Brackets 91, 921 andbosses 93 are provided thereon to support respectively a motor 95, a bearing stand 96, and pressure cylinders 97''. A series of bolts 98 serves to hold the box-halves in tightly packed engagement one with the other.

The mold gear 26 is engaged by a gear 100 mounted on a journal 101 and driven by a pinion 102. A fixture comprising the journal 101 is secured to the bracket 92 by a threaded shaft 103. The pinion 102, is mounted on asp-indie 104 supported by the stand 96 and coupled to, the motor 95. Bolts 195, 106 and 107- serve tosecure respectively the motor 95, the stand 96 and a guard 1118 for the gearing.

The cylinders 97 are directed at the axis of the mold 12, and have piston rods 110 disposed in abutting relation-. ship with the axle saddles 58. Screws 111 hold the cylinders in packed engagement with the bosses 93. Piping 112- communicates with the cylinders and a supply means for air or water under pressure. Pipe 115 communicates with a water disposal means and a duct 116 extending toward the spigot end of the mold. Pipe 117 communicates with a water supply means and a duct (not shown) similar to duct 116 but extending toward the bell end of the mold.

It will be noted that the lower box-half 50 is heavily I constructed and braced to resist the thrust of the cylinders 97 and provide a firm base for holding the mold 112 axially straight. The

axles

57, 60 extend from points near the ends of the mold to points near the middle of the mold, an arrangement well constituted to bend the mold as a beam. The pressure on the axles is distributed over wide areas and the critical supporting members (53, 6 1, 64, 65) are preferably made from a strong rust proof material such as nickel-chromium steel.

When centrifugally filled with molten iron, the mold is raised in temperature and expanded an amount that varies with any difference in heat-conductivity from spot to spot therein. The axis of the mold moves upwardly and the rods 110 are forced outwardly through the boxhalf 90, as the mold is dilated. If the mold tends to bow,

the pressure on each of the lower rollers fluctuates as the mold revolves but as long as the minimum pressure on each roller is greater than zero, no bowing is realized.

The mold is expanded about 0.04 inch per foot by the heat of the casting and enough to be injured thereby, if held rigidly. The pressure that may safely be applied by the cylinders 97 is therefore limited and best held to an amount little more than enough to keep the mold straight. Four rows of rollers are preferable to three because of the relatively less severe pinching action. The pressure required to hold a large mold straight is still considerable, especially if the mold is sprayed with an sulating compound and re-used as rapidly as possible without cleaning.

The necessary roller pressure is not as great, however,

4 as might be gathered from the behaviour of unrestrained molds. A mold for 12 inch pipe, 18 feet long, is held straight by a roller pressure, of some 4000 pounds, less than enough to remove a bow of 0.05 inch from the mold. If a mold is held constantly straight, the interior is abraded very little more on one side than the other as pipe after pipe is withdrawn .there-frorn. All sectors are heated about equally and expanded in a nearly uniform manner.

The power required to drive the sixteen rollers 55 is minimized by the novel type of grease seal employed, a seal that is not damaged by hot or dirty water and is capable of retaining a grease of low viscosity. The rings are preferably made of resin, reinforced with fabric and interspersed with graphite, When so made, the friction realized from these parts is very low; their useful life, measured in months.

The same non-metallic construction is well-suited for the thrust bearing 33-. The material employed for the curbing 44 is of relatively little importance if the packing journal 41 is made, as shown, somewhat smaller than the packing journal 22. The flange 45* is then normally disengaged from the curbing 44, by the unbalanced hydraulic force on the rotor 10-.

All molds for the same size of pipe are provided, preferably, with roller paths of the same diameter. The lower rollers are best aligned in the box-half 50 with the aid of a gage, e.g a specially prepared mold. Little or no allowance is made for wear since the roller paths are reduced but afew mils in diameter during the useful life of the mold (in terms of" product cast, about 2000 tons).

Changing fromone mold to another is conveniently accomplished by removing the box-half and rotating the upper axles 57 about the pins 68 until the arms 59 rest on the top face of the box-half 50; The rotor 10 can then be lifted from the lower rollers 55 and another rotor substituted. Piping 112, 115, 117 comprises swinginghoses and is not disconnected from the box-half 9.0 in this procedure.

In case a mold of a different diametrical size is to be substituted, certain appurtenances. are replaced; others, reused. The girts 25', 43 can be used for-more than one size of mold, as can the gear-and the rollers 55. The lower axles 60 are adapted to a second size of mold by simply inverting the stands 61 which have diametrically opposed bases for this purpose.

The larger the mold diameter, the greater the expansion and. the more diflicult is it tohold the mold straight by means of a surrounding sleeve. Post extending from the sleeve to the mold must be very loosely engaged or applied via springs. In either case, the bowing action of the mold is restricted but not suppressed. Superior castings can be produced by the aforedescribed scheme at no greater cost.

If the girth of the mold barrel is more than 25 percent as great as the length, the upper rollers can be safely omitted. In any case, the means revealed herein for taking the thrust of the mold and for mounting the lower rollers can be employed withbenefit. The extreme ends of the mold are well cooled, under the terms. The thrust bearing is. strongly supported and copiously lubricated. The rollers are readily adjusted, easily maintained.

I claim:

1. A centrifugal casting; machine which comprises, a long tubular mold, a box surrounding the mold, means for separating upper and lower halves of the, box, means for rotating the mold, means for resisting the axialmovement of the mold, and means for holding the mold axially straight; said holding means. comprising four rows of rollers engaging the mold, rotativlyat points equally spaced thereabout, each row containing at least four rollers and two axles for mounting the rollers in widespread pairs, stands supporting two rows of the rollers below the mold in laterally sliding relationship with the box, wedges controlling the laterally outmost position of the stands, means for supporting the other two rows of rollers above the mold in pivoting relationship with the lower box-half, and cylinders mounted on the upper boxhalf for pressing the upper roller axles toward the axis of the mold.

2. The machine described in claim 1 further characterized by having a thrust arm mounted centrally on each axle, and pockets disposed in the lower box-half for resisting the axial movement of the arms.

3. A centrifugal casting machine which comprises a long tubular mold with an enlarged end, a box surrounding the mold, means for separating upper and lower halves of the box, a gearing element mounted on the enlarged end of the mold, a guiding element mounted on the opposite end of the mold, rollers cradling the mold for rotation, and means for circulating water under pressure about the mold; said, guiding element comprising an annular hood disposed in packed relationship with the end-face of the mold, an axially split collar which cooperates with a shoulder of the mold and a series of screws in securing the hood, said collar having a rim which projects axially inwardly and engages the hood radially, a thrust bearing mounted in an annular niche defined by the inner end of the hood and the collar, a buttress mounted in the box for engaging the axially inner face of the bearing, a girt having radially packed relationship with the box and with a journal provided on the hood, and a flange mounted on the hood in spaced relationship with the axially inner face of the girt.

4. The machine described in claim 3 further characterized by said gearing element having a packing journal which is diametrically larger than the journal of the hood.

5. In a casting machine which comprises a long tubular mold, a housing, and rollers cradling the mold for rotation: stands supporting the roller axles and extending thereabove, struts mounted in the housing for sliding the stands thereon, brackets aflixed to the housing in laterally spaced relationship with the stands, upwardly flared wedges mounted on the brackets for controlling the laterally outmost position of the stands, screws depending from the bracket for adjusting the vertical position of the wedges, and means for resisting the longitudinal movement of the axles.

6. The construction described in claim 5 further characterized by said stands each having an inverted base and substantially the same configuration.

7. The construction described in claim 5 further characterized by having rings mounted on the axles between the stands and rollers, annular packings supporting the rings, springs mounted on the stands for pressing the rings against the rollers, and means for forcing grease into the roller while the mold is rotating.

References Cited in the file of this patent UNITED STATES PATENTS 1,988,470 Arnold Ian. 22, 1935 2,278,555 Myers Apr. 7, 1942 2,561,360 Goss July 24, 1951 2,586,349 Kurtz Feb. 19, 1952 2,790,997 Kurtz May 7, 1957 FOREIGN PATENTS 286,479 Great Britain Mar. 8, 1928 182,488 Austn'a July 11, 1955 531,346 Canada Oct. 9, 1956