US1683475A

US1683475A - littell

Info

Publication number: US1683475A
Authority: US
Publication date: 1928-09-04
Anticipated expiration: 1945-09-04

Description

Sept. 4, 1928. 1,683,475

- N. LITTELL PROCESS AND APPARATUS FOR CASTING Filed May 18, 1925 2 Sheets-Sheet 1 Sept. 4, 1928. 1,683,475

N. LITTELL PROCESS AND APPARATUS FOR CASTING Filed May 18, 1923 h 2 Sheets-Sheet 2 Patented Sept. 4, 1928.

UNITED} STATES NELSON LITTELL, F YORK, N. Y.

PROCESS AND APPARATUS FOR CASTING.

' Application filed May 18,

This invention relates to the casting of hollow cylindrical or cylindroid bodies and more especially to casting them with chillhardened interior surfaces.

One of the features of thi's'invention is the production of cast iron cylinders with chillhardened interior wearing surfaces, the remainder ofthe cylinder being of unhardened metal. By casting the cylinder aroundan internal chill orcore the inner walls thereof are made much harder than the walls of a sand cast cylinder, thereby giving greater strength and enhanced wearing qualities to the cylinder and at the same time permitting 'the thickness'of the cylinder walls and the weight of the cylinder block to be reduced. It is an object of this invention'to furnish a process and apparatus by which the cylinder may be cast around a chill core and the core withdrawn from the interior thereof. It is a feature of the invention that the cylinder is cast with a smooth internal bore of white iron which 'is nearer the ultimate size and shape desired than is possible with sandcast cylinders whereby the amount of boring or grinding necessary to fit the cylinder for use with a piston-is reduced. n

In accordance with one feature of the invention the cost of producing the cylinders is reduced by substituting a metal core which can be used many times for the sand cores now employed, which can be used but once.

A particular object of the invention is to provide an apparatus and process for producing an internal combustion engine cyl inder or cylinder blockhaving the improved qualiticsoutlined above. r I

The desirability of chilling the inner walls ofenginecylinders to cause them to offer greaterresistance to the wearing action'of the 'piston'and rings reciprocating therein has long been recognized, chilled cylinders have not been produced on a large scale however, because ofthe difliculty heretofore encountered in removing the chill core from the solidified casting. y 1

lVhen a cylinder is cast around a rigid stationary metal ;core the contraction of the mctal is apteither to cause the casting to 1923.; Serial a... 639,771.

by the use of'contracting metal cores which are designed to accommodate the shrinkage of the metal. However, the expense involved in the use ofsuch elaborate or delicate degeneral adoption of vices has prevented the such schemes.

In accordance with the preferred form of the invention molten metal which is to form the cylinder casting is poured around a rigid metallic chill core which may have a very slight taper in the direction from which it is withdrawn and the core is withdrawn gradually from the interior as the pouring progresses. The speed of withdrawal and the taper of the core are so correlated with the rate of pouring and the contraction. of the casting that the core does not bind in the -casting;'and the length of the core is such in continual motion relative to the casting throughout the pouring and until removed from the casting. which is a very important factor in preventing the binding of the castinc, around the core.

For a clearer understanding of the nature and mode of operation of the invention, reference may be had to the drawings which 3 illustrate the preferred form thereof.

Fig. l is a part vertical sectional view illustrating the casting'of a water cooled cylinder block for an internal combustion engine,

showing the core slightly withdrawn from the mold cavity.

Fig. 2 is a similar 'view illustrating the casting operation near completion;

F ig. 3 is a view similar to Fig. 1, taken on line 3-3 of Fig. 4, illustrating the invention 'asapplied to the cast-ingof an air cooled cylinder Fig. 4 is a sectional view on the line 4-4 of Fig. 3; y

F ig. 5 is a sectional View of an artifically cooled or heated chill core. 7

In Figs. 1 and 2. 1 illustrates a sand mold for the casting of a cylinderblock, which mold consists of a base board 2, an intermediate section 3 and a cope 4. The base board 2 may beentirely of metal or be of sand, dry or green, with a metal or wooden tion 3 is preferably made of greensand and 'supportas illustrated; the intermediate secthe cope may be of sand or metal as prefer red. As illustrated the cope -ilis separated from the intermediate section 3 by a thin metal plate 5, which prevents sand displaced from the cope by the withdrawal'o't the cores :lrom dropping down into the mold cavity. (3 is a thick graphite facing to further prevent displacement of the sand in the cope. The plate 5 may oi course be omitted and only the lining 6 used to insure a. clean draw oi? the core from the cope.

The cylinder is cast about a rigid chill core 7. This core is longer than the cylinder to be cast, and may be provided with a slight. taper toward the top, as illustrated in an exaggerated way in Fig. 1. The core 7 is provided with a threaded stem 8 which is adapted to pass through perforations in,

plate 9, and. to be adjustably locked to said plate by lock nuts 10. The plate 9 is locked in a similar manner to the piston rod 11 of piston 12 which is reciprocable under suit able pressure in the cylinder 13. The pressure medium is conducted to either side of the piston by pipes 14: and 15 and is controlled by a two-way valve 16. The sprue hole is illustrated in dotted lines at 17 in Figs. 1 and. 2, and is adapted to introduce the metal at the bottom of the mold cavity, or in case the metal freezes in the bottom, to introduce i tinto the top of the mold through auxiliary passagmvays 18. 19 and 20 illustrate sand cores for forming the water jacket around the cylinder walls.

In operation the mold is assembled as illustrated in Fig. l and the chill cores are projected through the mold cavity and into the cope as shown at 21, where the cores are illustrated as being slightly withdrawn from the top of the mold cavity. The lock nuts 10 and 22 enable the cores to be adjusted so as to control the distance they will project heyond the mold cavity into the cope, and the cavity Ql is termed of suitable depth to accommodate same. ,Then the pom'ing is started and simultimeously therewith, or after a short lapse of time, the pressure medium is admitted. to the upper side of piston 12 to gradually but forcefully withdraw the cores 7. The molten metal coming into the mold and striking the chill core, almost immediately skin frozen and the core is forceably but gradually withdrawn before the casting has time to shrink thereon. The taper oi? the core and the speed of withdrawal may be such that the casting may shrink at its natural rate as the core is withdrawn. thereby avoiding all unnatural stresses; and will not bind upon the top or any intermediate section of the core. The core is of such length and its withdrawal so slow, that the pouring will be completed and the top of the casting skin frozen sutliciently to hold its shape be fore the top of the core is withdrawn below the top casting. Fig. 2 illustrates the core partially withdrawn and shows the chilled condition of the cylinder walls. It is important that the core be kept in con tin ual motion until it is clear of the cylinder walls.

3 and l illustrate one way of applying the invention to the casting of cylinders with radiating and cooling fins, illustrated here with the head integral. In these figures, the mold consists of a drag 23,'cheek 2i, and cope 25, the drag and cheek are preferably sand and the cope is preferably metal, although sand may be used for thepurpose. 26 illustrates the chill core which in this cmlaalimcnt is withdrawn from above the mold by means of rod 27 and piston 28 operating in pressure cylinder 29. 3O illustrates a refractory lining for the pouring basin in cope through which the metal is poured into sprue 31. The cylinder wall is illustrated at 32 and the fins on the sides and top thereof are shown at 33. In the embodiment shown these fins are castintegral with the cylinder wall, however, they may be made of preformed inserts of high heat conductivity placed in the walls of the mold so as to protrude into the casting cavity and becomewelded in the cylinder wallwhen same is cast. In this modification the bottom of the mold cavity is allowed to fill be fore the withdrawal of the core is started.

The-cores 7 and 26 may be solid cylinders indicated in Figs. 1 to 4:, or they may be artificially heated or cooled as illustrated in it 5, wherein 7 indicates an artificially cooled core of proper length and taper, consisting of an outer casing 34:, an inner casing 35, and a flexible conduit 36 tov introduce a cooling or heating medium between the casings fi l and 35, and to withdraw it from casing at outlet 37. The core may be coated with a mixture of graphite and oil, clay wash, or some other suitable protector, before each casting operation.

In the embodiments shown the mold is stationary and the core is withdrawn longitudinally therefrom, however the invention is not limited to such arrangement as the core may be given a compound rotative and loiuritudinal movement, or the core may be the stationary element and the mold moved relatively thereto.

As indicated by the shading of Figure 2, the in vcntion provides a cylinder the inner wall of which is of chill hardened metal, shading oti' into ordinary grey iron which strengthens and reinforces the chilled inner walls to enable'them to withstand the pressure of the explosions in the engine cylinders.

The term chilling as used in the specification and claims of this application (when not used in referring to the core 7) refers to that property of cast iron and certain other alloys which, when rapidly cooled or chilled from a molten state, solidify with part of the carbon in combination with the iron, forming a dense hard. white ironknown as cementite, as distinguished fromthe properties of the same alloy when cooled slowly from a molten state, which slow cooling of cast iron permits the carbon to separate from the iron as graphite, forming grey iron. Inasmuch as certain other alloys in addition to cast iron exhibit this property of chilling, as, for example, certain aluminum-silicon alloys, the invention, is not necessarily limited to cast iron, and the construction may be used to produce cylinders without an internal chill if desired. I

The invention is not limited to the casting of internal combustion engine cylinders or the apparatus illustrated herein, but coning skin of the casting has-solidified, but before the casting shrinks upon the core, the withdrawal of, the core commencing soon after the pouring is started and continuing until after the pouring is completed.

2. The process of casting iron cylinders which consists of introducing a molten iron mixture into a refractory mold around a rigid metal core and withdrawing the core after theinner surface has solidified, but before the casting has shrunk upon the core.

3. The process of casting grey iron cylinders with a chilled inner surface which consists of introducing a molten cast iron mixture into a refractory mold around arigid chill core and withdrawing the core after the inner surface has solidified, but before the casting has shrunk upon the core, the withdrawal of the core commencing before the pouring is completed.

' 4. The process of casting grey iron cylinders with a chilled inner surface which consists of introducing a molten cast iron mixture into a refractory mold around a rigid chill core and gradually withdrawing the core after the inner surface has solidified, but

before the casting has shrunk upon the core,

the withdrawal of the core commencing simultaneously with the pouring, and continuing until after the pouring is finished.

5. The process of casting engine cylinders with a chilled interior which consists in pouring a molten chilling alloy into the mold around a rigid chill core extending through the mold cavity and projecting there beyond and withdrawing the core, the withdrawal commencing substantially simultaneous with the pouring operation and being of such speed that the pouring is completedand the interior of the casting is solidified before the projecting end of the core passes the end of the mold cavity.

6. The process of casting internally chilled engine cylinders which consists in pouring a chillable metal into a refractory mold around a rigid tapered chilled core which projects beyond the mold cavity, and withdrawing the core longitudinally from the mold, the withdrawal commencing soon after the pouring is started and being ofsuch speed that the end of the core does not pass the end of the mold cavity until the pouring is completed, and the chilled skin of the casting solidified, and the taper of the core being such that .the casting in shrinking will not interfere with its withdrawal.

' 7. The process of casting jacketed engine cylinders with a hardened interior which consists in pouring a chilling mixture into a mold shaped to form a acketed casting and provided with a metal core and withdrawing the core from the mold and casting as the skin ofthe casting solidifies.

8..In a casting apparatus the combination of refractory mold, a mold cavity therein, a cooperating tapered meta-l core extending through the mold cavity and projecting outside the mold, and power means attached to the core outside the mold for causing the withdrawal of the core from the mold through the lower end of said mold, said withdrawing means operating in such relation to the pouring of the metal into the mold, that the pouring is completed before the top of the core passes below the top of s V the mold, the degree of taper of the core and the time of operation of the withdrawing means being relative to the degree of contraction of the body of metal cast in the mold, during the process of cooling.

7 In testimony whereof I affix my signature.

NELSON LITTELL.