US1501338A - Rotary casting - Google Patents

Description

July 15 A. M. HENRY' ROTARY CASTING Filed Oct 9} 1925 IN VEN TOR n/ A. M. HENRY .ROTARY CASTING 3 Shasta-Shem 2 Filed Oct. 9, 1923 INVENTOR A. M. HENRY ROTARY CASTING .Bufl 15 1924.

Filed Oct. 9, 1925 s Shets-Sheef. 5

INVEN TOR Patent July 15, 1924,

AUGUSTUS M. HENRY, OEIBROOKLYN, NEW YORK.

ROTARY, oas'rme;

Application filed October 9, 1923. Serial No. 667,524.

To all whom it may concern.

Be it known that I, AUoUs'rUs M. HENRY,

a citizenof the United States, and a resident of thecity of New York, borough of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful. Improvements in Rotary Castings, of which the following is a full, clear, and exact description.

The present invention relates to the art the same will be case-hardened where contacted by all or some of the walls of the mold cavity.

Another object is to provide a method and apparatus as above, wherein the mold is formed of or has its cavity lined or'faced with a material which is practically as inexpensive and as easy to machine smoothly and nicely to shape, ets giis iron or steel; which material is madefup of masses of granular components as tenaciously cohe sive as iron or steel but yet a material adapted to be machined or pressed into a mold or mold-part not having the liability of a similar iron or steel part to crack, chip and distort from molecular growth as the result of repeated-heat-shocks, i. e., as the result of repeated casting operations,-thus truly providing a permanent rotary mold; which material may be absolutely depended on to give up some of its own content to the contacting superficies of the molten metal impacted against the mold by centrifugal force at each casting operation but not enough thereof to preclude the mold from being. employed for makin a great number of castings having only a solutely negligible variations of contour, bulk and weight,

such donated content constituting the carbonaceous matter for co-acting with the heat of. the metal incident to its molten state, thereby to predetermine that the casting when ejected from the mold and merely anlowed' to cool on the floor of the foundry will be case-hardened accordin to the' in-. vention; and which material will not, like iron or steel; chill the casting as an iron or steel mold always does. Such a material, I have discovered, is carbon, preferably densely compacted; such for instance, as is known as gas carbon and as is used for making carbon-electrodes for electric arc lamps or for making the commutator brushes for dynamos, motors and the like.

To explain the practical and salient distinctions between a chilling and a case hardening of a ferrous casting: When such a casting is chilled, the term is used, herein and indeed generally, to describe what happens to the superficial layer of a fairly large mass of cast iron when such mass is cast and such layer is solidified against e a metal mold. Said layer, obviously, has the same carbon content as the rest of the casting, except that the layer has its carbon in the combined form and the carbon of the mass of the casting underlying such layer is largely or wholly graphitic; On the other 7 hand, case-hardening as hitherto racticed,

has involved (a) the making, usua if not always in a sand-mold, of a soft iron casting, that is, a casting having therein a more or less uniform distribution of carbon largely or wholly in the graphitic form throughout; and (b) the application to the superficies of such casting, some time after removal from the mold and generally some time after the casting has been permitted to cool, of a carbonaceous material, as powdered charcoal, and a simultaneous heating of the casting to"a point where the outer cuticle of the casting is converted into a high-carbon steel by .the cementa'tion process, or, in other words, to a point where the mere ,skin of the casting is chemically carburized and 'such skin becomes a hard, strong case for the inner metal mass of the casting. Such case, obviously, has a different and greater carbon content than the rest of the casting; as contradistinguished from the conditions prevailingin a chilled casting, where, as stated above, the outer chilled layer has the same carbon content as'the inner mass of the casting, and, further, the

carbon of the chilled layer is carbon in the combined form and so resulting in a layer very solutely no malleability. 4

brittle and of little toughness and ab- As a result of the fact, then, that the present invention provides a casting which is case-hardened merely,and not chilled as above, and a casting, moreover, having immediately below its casehardened skin a uniformly close dense grain uninterrupted by air or blow-holes and deposits of slag and other impurities and with no portion harder or softer than another, which latter qualities are characteristic of all centrifugal castings, there is provided by the invention a method and apparatus particularly adapted, thereby to attain a special object of the invention, for making rapidly and economically, and in a permanent mold, cast-iron rims or tires for car, truck, locomotive and the like wheels. for railroad rolling-stock, which tires will be, as the result of the casting operation solely, tougher than steel,-practically as strong, and case-hardened attheir track-engaging surfaces pursuant to the requirements of the present practice; while at the same time said tires will, on the one hand, be unhardened at their inner peripheral portions, to permit them to be easily machined to the characteristic stepped shape thererequired and, on the other hand, chilled in no part, The importance of the last statement cannot be too much emphasized; as a chilling of the portion of the casting formed against the mold walls, and hence a chilling of thatpart of a centrifugally' cast rim subsequently to ride on and alongside the rail, provides always a railroad carwheel which dare only be used with risk of serious accident. This is so because a chill is a hard external layer of the casting of such measurable thickness, and of such great brittleness, as to be extremely liable to originate a crack deep enough to extend itself into and through the entire thickness of the casting.

Another object of the invention is to pro-. vide, further, a casting apparatus of the rotary type particularly adapted for facilitating the method of the invention and for maintaining continuously the rapid production .of case-hardened ferrous castings as above, and a comparativel simple and inexpensive apparatus where y such speed of production may be so maintained and without endangerin the integrity "of the mold proper, prefera ly of carbon as above, by repeated removal'of a completed'casting at half-minute intervals or less.

Referrin now to the accompanying drawings, wherein are illustrated a preferred embodiment of such apparatus, and an illustrative method of casting facilitated thereby according to the invention,

Fig. 1 is a side elevation of said embodiment, partially broken away and partially in section;

Fig. 2 is a transverse section, taken line 2-2 of Fig. 1;

on the Fig. 3 is a top plan view, on an enlarged scale, and looking down on the top of the mold as viewed in Fig.- 1, according to the arrow 3 in said Fig. 1.;

Fig. 4 is an enlarged detail view showing the mold-structure and its interior parts.including the carbon mold pieces, this view being an axial section; and

Figs. 5, 6, 7 and 8 are diagrammatic views indicating successive operations and adjustments of the various parts in making and ejecting a casting.

Similar reference characters refer to similar parts throughout the several views of the drawings.

The apparatus shown includes a rotor structure including a main driving or moldsupporting shaft 20, a mold structure to be hereinafter described, the armature, fixed on said shaft, of the driving motor 23, and certain other parts to be mentioned in a moment. I

Shaft 20 is journalled on suitable antifriction bearings in a central sleeve casing 24, which casing carries a plate-extension 25 on which the motor-stator or case is fixed.

This main casing 24 is, by-oppositely offset stub-shafts one of which is shown at mounted on a horizontal axis relative to a pair of A-frames 27 bolted attheir feet to a concrete bed 28 and constituting the supporting framework for the rotor-structure.

The mold-structure includes a metal-fixture 29, fixed on the upper end of shaft 20, and an upper metal fixture 30 held to rotation with the shaft 20 of the lower fixture 29 'as follows: Acylindrical steel pin or stud 31 isset tightly in the lower fixture to'protrude above the flat annular surface 29 of the latter and on which rests a similar surface 3O of'the upper fixture; such pin being somewhat loosely received in a cylindrical will be noted that the lower fixture is annularly recessed beyond the central plain portion, such recess for receiving and centering theblock 33 before securement of said block in place; and that the upper fixture is centrally conically cut away as indicated at 30', for permitting the introduction of the molten metal, and also for providing a peripheral inner edge with which the inner p'eriphery of block 34 may-be registered to cenflange, so that a metal clamping ring may be applied over such flange of the block 33 and'a similar ring 36 may be applied under such flange of the block 34. Through suitable matching apertures in these flanges and rings and into likewise matching tapped recesses in the upper fixture, are applied screws as indicated at37 and so that these screws may be applied to clamp the rings 35 and 36 without danger of injuring the flanges of the carbon blocks engaged thereby, spring means as indicated at 38' are carried by the screws, such means including a plurality of alternately arranged slit or spring washers and lane discs as shown. Preferably there are our of such screws and spring-equipments applied relative to each ring 35 and 36,1sipaced apart circumferentially of the mo In order to insure further that the carbon block 34 will not shift relative to the metal parts of the mold, a plurality of shallow cylindrical recesses are cut in the fixture 30 opposite the portions of the carbon block 34 of maximum thickness, as indicated at 39; and in each of these recesses is nested, as illustrated, a split or spring washer of such dimensions and stiffness that when the block 34 is clamped to the mold by ring 35, a canted end of each washer in a recess 39 will'bite into but not endanger the integrity of the block. Preferably there are six of such recesses and .washers, spaced apart 60 circumferentially of the mold.

Means for axially separating the moldfixtures 29 and 30, always parallelly, and different degrees as required, is provided as follows: Matching projections 29 and 30" are offset from the two fixtures, three of such projections being preferably provided, spaced apart circumferentially of the mold. Over each projection30", upper moldfixture 30 carries rigidly a plate or cave-projection 30. Each projection 30 is provided with a smooth transverse bore of suflicient diameter to receive, with slightly more looseness than characteristic of the reception of the upper part of a stud 30 by its recess 32, a smooth cylindrical portion 40 of a shaft S; and each projection 29" is drilled and tapped inline with such bore to provide a tapped bearing for a screw 41 forming another portion of said shaft S. Said shaft S, at what may be termed its upper end, terminates in an enlarged head nested loosely between the eave-projection 30 and projection 30 of the upper fixture. Said shaft carries, below its screw length 41, an elongate pinion or cylindrical rack 43; below this rack, a smooth cylindrical portion 44 is journalled in a suitable bearing in a disk 45 carried rigidly by main shaft 20, and below such disk, has a squared end to which may be applied a crank (not shown) to facilitate rotating the shaft S. The three pinion racks 44 of the three shafts S all mesh with a spur gear 46 revolubly mounted by .way of a suitable anti-friction bearing on said main shaft 20 but restrained from endwise movement relative to said main shaft.

It is obvious that by applying the crank last-mentioned to the squared lower end of the shaft S most conveniently accessible at the moment, at cessation of rotation of the rotor-structure at the conclusion of a casting operation, such crank may be turned to separate the two mold-fixtures 29 and'30, always parallelly, to the extent of separation desired,such, for instance, as first to move such fixture apart as indicated in Fig. i

6, next to move such sections apart as indicated in Fig. 8, and next to restore such sections to the close contiguity required for casting.

It is observed at this point that the flats of the A-frames 27 are obliquely inclined relative to their floor-plates or feet 27 so as to insure that such flats will diverge in a downward direction when the floor plates 27 are bolted to the foundation bed 28; thus to permit the entire rotor-structure to be variously swung about the horizontal axis afforded by shafts 26 as shown in certain of the views last-mentioned and for a purpose which'will be explained under Operation hereinbelow.

In order to adopt the shafts S and their associated mounting and restrainingdevices, to act automatically to maintain the mold fixtures 29 and 30 in the'close contiguity 1.

above-mentioned, at all times "during rotation of the mold, the following means is provided: Fixed on the portion 44 of each such shaft, is an offset ball 48 of sufficient weight and so disposed that its center of'gravity is to, one side ofa straight line joining the axes 'of the associated shaft S and main shaft 20 when the mold-fixtures are manually brought to said contiguity, so that rotation of the mold-structure in the predetermined direction will always cause centrifugal force to act on these balls to cause them to apply turning moments to the shafts S to hold the moldfixtures close together.

Operation: With the mold-structure rotating at the proper speed, preferably about an axis inclined 45 asshown in Fig. 1, a predetermined charge of molten metal is delivered to the mold as indicated by the ab shafts 26 to dispose main shaft 20 as shown in Fig. 6. Thereupon, aworkman applies his crank to the squared lower end of a shaft S, and turns such shaft and crank to separate the mold parts as shown in Fig. 6. Thereupon, the same or another workman, by the use of a suitable apparatus, appliance or fixture (not shown), slides into place a sheet metal shield 49 of any suitable outline, but preferably equipped with a layer of wood-below the metal and a sheet of asbestos below the wood. Such shield is shown in place in Fig. 6, but with the three strata just mentioned not delineate-d or marked off; it being understood, however, that the asbestos stratum corresponds in location with the lower bounding line of the shield as shown in this view, so as to preclude any possible chilling of the casting. It should be particularly noted that the matching flat annular surfaces of the two carbon blocks and of the two mold fixtures which mountthe latter, are now at different levels and so disposed relative to the now upper most surface of the casting, that all parts of both blocks are protected against accidental danger by contact with the shield. With the parts thusarranged, the same or another workman next rotates such structure through 180 about shafts 26, to'dispose the shaft 20 as shown in Fig. 7. Thereupon, the same or another-workman applies his crank again to the squared end of a shaft S,

and turns such shaft and crank to separate.

the'mold parts as shown in Fig. 8. Whereupon, finally, with the shield suitably restrained aga-inst sliding movement relative to the mold, the casting is pushed or pulled in the directi'onof the arrow 50, clear of the shield and the mold, and left to cool before i being sent to the machine-shop for final finishing of its internal periphery.

As to the various processes of the present invention, these will be understood from the foregoing description of the apparatus shown in the drawings. In this connection, it is particularly to be understood that the present invention is of course not necessarily to be limited to'the making of rims or tires for car-wheels, of'iron or steel, but may be applied to make other articles of annular cross-section, by which is meant either ringshaped or sleeve-shaped articles, as, for instance, the so-called economizer sleeves for boiler and superheater tubes and the like, journal boxes, mouths for steel tanks, and other articles to be investigated as articles of arcuate cross-section, for making, say, railway brake-shoes; as is indicated by the scope of the appended claims.

By the expression cross-section as used herein is meant a crom-section through the casting which would be taken, with the casting still unejected from the mold, in a plane perpendicular to the axis of rotation of said mold.

As to the apparatus shown, obviously variations may be freely resorted to within the scope of the said claims. 7

In said claims, wherever a mold or mold part is characterized as permanent, there is meant merely that said part is of a material or so constructed that the part will not be so injured by a single casting operation as to be useless for a second casting operation, as contradistinguished from a mold or mold part constructed or lined with ordinary foundry sand.

I claimi 1. A method of formingferrous-metal articles which involves providing a mold having a cavity shaped to correspond with .the predetermined external shape, of a desired article, rotating the mold and thereafter admitting-molten metal thereto, and thus utilizing centrifugal force to form a casting in said cavity while simultaneously applyingto the portions of molten metal impacted by centrifugal force against the shaped arts of said mold cavity, a material to casearden the resulting casting as to portions thereof formed by such shaped parts.

2. A method of forming ferrous-metal articles which involves providing a mold having a cavity shaped to correspond with the predetermined external shape of a desired article, rotating the mold and thereafteradlnitting molten metal thereto, and thus utilizing centrifugal force to form a casting in said cavity while simultanepusly, applying to the portions of molten metal impacted by centrifugal force against the shaped parts of said mould cavity acarbonaceous material.

3. The art of manufacturing ferrous vmetalocastings by the rotary casting method, which method involves providing a mold 4. The art of forming ferrous-metal articles bythe use of a permanent mold, which method involves providing a lining for said mold including a plurality of pro-shaped mold,

blocks of gas-carbon to constitute the 'permanent mold proper, rotating the mold, and introducing molten metal into the rotating mold and treating such metal during solidification to case-harden the resulting casting in certain portions practically simultaneously with the creation of said casting.

5. The art of forming ferrous-metal articles by the use of a permanent mold, which method involves rotating said mold and introducing molten metal into the mold and treating such metal during solidification to case-harden the resulting casting in certain portions practically simultaneously with the creation of said casting.

6. The art of forming ferrous-metal articles by the use of a permanent mold, which method involves introducing molten metal' into the mold and treating such metal during solidification to case-harden the resulting casting in certain portions practically simultaneously with the creation of said casting, and removing said casting from the mold while still retaining sufficient heat to insure self-annealing of the casting by such heat after removal of the casting from the thereby to graphi-tic carbon of the combined carbon in any chilled portion of the casting.

7 In rotary casting apparatus, the combination of a rotary mold including a plus rality of separable parts, means operable at will for bodily moving one of said arts relative to the other and also operab e at will for adjusting said parts to ditfere'nt'degrees of separation, and centrifugally actuated means for locking said parts in predetermined adjacency during rotation of the mold.

8. In rotary casti'ng'apparatus, the combination of a rotary mold including a plurality of separable parts, and means oper-.

able at will for bodily moving one of said parts relative to the other and parallelly thereto.

9. In rotary casting apparatus, the combination of a rotary mold including a plurality of separableparts, means operable at will for bodily moving one of said parts relative to the other, said means including impositive adjusting means of the screw type, and centrifugally actuated means automatically operating to lock the mold parts securely in predetermined adjacency during rotation of the mold.

10. In rotary casting apparatus, the combination of a rotary mold including a plurality ofseparable pa'r'ts, means operable at will for bodily moving one of said parts relative to the other, said means including an element revoluble about an axis different from the axis of rotation of the'mold, and centrifugally actuated means for automatiinsure conversion to cally forcing said mold parts into close adjacency during rotation of the mold.

11. In rotary casting, the combination of a rotary mold including a plurality of axially separable parts, rotating means on which'one of said parts is secured. operating means for axially separating the mold parts including an element bodily moved with the first-mentioned part during operation of said rotating means, and a foundation structure on which said rotating means is mounted for rotative adjustment about a substantially horizontal axis,

12. In the art of making rotary castings of ring form by the use of a casting apparatus including a mold having a pluralit of axially separable mold parts, journalling means for rotatably supporting the mold, means for separating the mold parts by-different amounts, and a foundation structure on which said journalling means is rotatively adjustable about a substantially horizontal axis; the method of operating such apparatus, which comprises utilizing the mold to cast a ring-form article therein,"

thereupon, while said journalling means is positioned to support the mold thereabove, separating the mold parts a certain amount, thereupon providing a sheet-like shield and inserting said shield between the mold parts and to overlie the casting, thereuponrota'- tively adjusting said journalling means to dispose the mold therebelow, thereupon further separating the mold parts, and thei'eupon ejecting the cast article by moving the latter relatively'to said shield and the mold in a directionsubstantially perpendicular to the mold axis.

13. The method of producing ferrous metal articles from a molten charge which consists in forming a casting by centrifugal action in .a shaping mold, and. simultaneously applying case-hardening material to parts shaped by the mold.

14. The method of producing ferrous metal articlesjfrom a molten charge which AUGUSTUS M. HENRY.

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