US1699120A - Metal casting and method of making the same - Google Patents

Description

Jan. 15, 1929. r 1,699,120

(1. E. REINHARD T METAL CASTING AND METHOD OF MAKING THE SAME Filed June 20, 1923 4 Sheets-Sheet l Inventor Carrol E Reinhardt .11 9 B5 Wm, M

' Attorney-i.

Jan. 15, 1929.

C. E. REINHARDT METAL CASTING AND METHOD OF MAKING THE SAME Filed June 20, 1923 4 Sheets-Sheet 2 H H I i I i I I 04M MW "Mn- 33; 29

25 L I a Inventor, CeTroI E.Relnhardt.

Jan. 15, 1929.

C. E. REINHARDT METAL CASTING AND METHOD OF MAKING THE SAIIE 4 Sheets-Sheet 3 Filed June 20, 1925 Inuentor Carrol EReinha d 40 B9 75 Atror'neqs Patented ,J an. 15, 1929.

UNITED STATES E. REINHABDT, OF MONTREAL, QUEBEC, CANADA.

nun cas'rmc AND amison or MAKING zrnnsm.

Application filed June 20,

My invention relates to metal castings and a method of making the same and more particularly to making sound metalcastings 111 molds that obstruct thenormal shrinkage and contraction of the casting while cooling and solidifying. According to methods hitherto used, such obstructions to normal contrac-, tion and shrinkage resulted in fiawing the casting and caused cracks, fissures or undue 1o stress in the esulting product. The new method herein described enables such castings to be made in rigid molds, substantially free of cracks, fissures or undue internal stress.

Heretofore in making castings in molds of such shape that they tend to obstruct the necessary shrinkage of the metal in solidifying and cooling, the'molds or parts thereof have been made of some compressable or r crushable material (e. g. sand molds) whereby when contraction takes place in the cast,

any part of the mold which obstructs the same, is intended to yield or collapse and so permit the necessary contraction to take place, without substantial injury to the casting. The mold, however, is more or less destroyed, so that anew mold is required for each casting, and also parts of the cast-ing do not have the smooth or finished surface produced when the casting is formed in a metal mold which does not so yield or collapse and Where obstructing surfaces are rigid' and smooth. Thus with my invention metal molds may be used a great number of times and all proportions and sizes remain correct.

urthermore, a better grade of product is produced, the same having to a considerable extent the qualities of wrought metal rather than cast. By my invention much of the ex- 40 pensive machining, grinding and trimming up of the casting is avoided.

My process consists in the application to poured or cast metal before solidification is complete of a pressure of such Value and duration and applied over such area or areas as to prevent the formation of fissures, cracks, or undue stress in the cast during the cooling of the metal.

The benefits of the invention may be illus-v 0 trated ina simple manner by considering the casting of a straight bar, assuming that the cast is in plastic condition, but is held fixedly at its ends by means of rigid projections in the mold or in any other manner. The metal in cooling will contract, but being held at the ends, the contraction at the ends is thus 0b- 1923. Serial No. 646,517.

structed. Therefore, the bar, if allowed to cool according to old methods, will either be cracked at some point intermediate its ends, or will have an inherent tensile stress somewhere along its length. If to the same bar while plastic pressure is applied according to my invention, the developing shrinkage will be compensated or offset,- and upon cooling the bar will be free from fissures, cracks or undue stress. The same principles, I believe, apply with equal force to a continuous peripheral band like a wheel tire or to any open work or flanged casting and also, of course, to long large bars of certain irregular section in which solidified parts of the cast introduce obstructions to the contraction of parts solidifying last.

Another advantage of this invention which is obvious from the above and from examples given later, is that this method of casting provides a way of shrinking on and thus rigidly attaching an enclosing casting to a rigid article, e. g., a steel tire on a cast-iron wheel centre. All that is necessary is to place the rigid article, adapted to fit into and become a part of the casting in its proper position within the mold and then to pour the metal around therigid article, suitably sealing the mold and applying to the solidifying metal a pressure of such value and duration and over such area or areas,'as' to" swedge the solidifying metal into position and cause the solidifying metal 'to flow whereever natural shrinkage is obstructed, and maintaining such pressure substantially throughout the period of solidification, where after the solidified metal will elastically contract upon and ductilely stretch itself about the enclosed object, without creating undue stress that might form cracks or fissures, because after solidification it acquires sufficient tenslle strength to be shrunk on without flawing. To further insure such a shrink-fit from slipping, the enclosed metal article may be recessed. In this manner, metal articles may be enlarged, by using them as rigid cores, and casting by my process a surrounding portion of swedged metal of the same or different kind thereon or thereabout, and causing the new cast to overlap, grip or interlock with the said article. When and if necessary, specially designed webs, flanges, studs, keyways, or other recessesor projections may be provided to secure complete interlocking, but in all cases the forcing or swedging to overcome the weaknesses produced by shrinkage during solidification is characteristic of the application of my invention to such interlock castings.

The process .may be applied in the manufacture of many different kinds and forms of castings including. among others, railway car wheels, locomotive and car wheel tires, car bolsters, side frames, end sills, draw bar yokes, coupler-knuckles, centre plates, dipper teeth, gear wheels, manganese-steel, track work and the like. Further and more specific objects,. features and advantages will more clearly appear from the detail description given below taken in connection with the accompanying drawings which form a part of this specification and which illustrate the application of the invention to certain forms of castings and from which those skilled in the art will readily understand the applicability of the invention in the making of other kinds and forms of castings. I

In the accompanying drawings Fig. 1 is a vertical section of a mold in which a tire is to be cast on a car wheel; Fig. 2 is a similar view of a mold for casting an entire car wheel; Fig. 3 is a perspective view of a column guide that may be cast by the process of this invention; Fig. 4.- is a plan view of the mold in which the column guide is cast, showing the plunger for effecting the pressure; Fig. 5 is a vertical section on the line 55 of Fig. 1; Fig. 6 is a vertical section on the line 6-6 of Fig. 4; Fig. 7 is a perspective of a car truck side that may be cast according to the process of this invention; Fig. 8 is a vertical longitudinal section of the mold and plunger for casting the truck side, showing a section of the truck side on the line 88 of Fig. 7 Fig. 9 is a vertical transverse" view of the mold in which the truck side is cast showing a section of the object on the line 9-9 of Fig. 7; Fig. 10 is a perspective View of a portion of a crane rail bridge and Fig. 11 is a transverse vertical section of the apparatus for casting the crane rail bridge. Fig. 12 is a similar view of a mold, showing a gear-wheel blank with a toothed rim about to be cast on; Fig. 13 is a partial section of a mold in which an outer ring is to be cast onto the drag section of another mold; Fig. 14 is a perspective view of a shank and cast-on dipper tooth; Fig. 15 is a plan view of the mold in which the dipper tooth is cast on the shank; Fig. 16 is a vertical section on the line 6-6 of Fig. 15;,Figp17 is a perspective of a reinforced brake shoe consisting of a wearing plate and a reinforcing back; and Fig; 18 is a transverse vertical section of the apparatus for casting the back to the wearing plate, showing a section of the brake shoe on the line 11-11 of Fig. 17.

Referring to the accompanying drawings by corresponding reference characters throughout, the numeral 1 indicates, in general, a, mold comprising a cope section 2 and drag section 3 in which a tire is to be cast upon a car wheel centre 4. The cope section includes an inner ring 2' connected integrally therewith by means of webs 5. The centre 4 is positioned by a cone shaped core 6 seated in the drag section. The cope and drag sections are extended as at 7 on one side to provide an opening for a gate 8 and a gate cutter 9. The gate is lined with sand 10, and the complete mold is slid when desired onto a press 11. A pressure ring 12 is disposed in the cope section between the body portion thereof and the inner ring 2'. The pressure ring is provided with slots 13 which receive the webs 5 and permit vertical movement of the ring. The base of this ring is completely covered with an attached metal ring 14 which may be renewed as required.

The metal is poured into the gate from a ladle, or in any other desired manner. As the metal is poured the gases in the mold escape through vents 15 in the cope section. The pressure ring is held in raised position by means of a pin 16 driven into an aperture in the side of the ring and resting on t 1e cope 2. When the matrix of the mold is entirely filled and the pouring ceases, the complete mold is moved to correct position on the press 11 as shown in Fig. 1. The ram 17 of the press is then forced downwards making contact with the gate cutter 9, which cuts off the gate and substantially seals the mold by cutting through the sand lining, and locking into a recess 18 in the bottom of the extension 7 before the ram makes contact with the pressure ring 12. Upon engagement of the ram with the pressure ring the pin 16 is sheared and the ring is forced downwards upon the molten or plastic metal in the mold and seals the vent opening 15. lVhile the metal is solidifying and cooling it is held under pressure by the ring, so that no cracks or undue stress is permitted to develop in the metal cast. during solidification. The press ram may now be moved upward and a hook 19 suspended from the ram engages a bar 2 on the inner ring 2'. Further upward movement of the ram lifts the entire cope section, leaving the finished product resting in the drag and ready to be removed from the mold in any suitable manner.

The tire which is still quite hot must shrink or contact around the centre, and as the latter will not permit of the tire contracting freely, the metal must elongate or stretch. To provide for this action the tire must be of such physical property as to possess a percentage of elongation that exceeds its coefficient of contraction. An elongation of only 2% is suflicient whereas all ordinary steels may be elongated much more than 2% without injury.

A modification of the same method adapted to form a car wheel is shown in Fig. 2. This mold, like the one used in casting a tire on a wheel, is made entirely of metal except for the sand at the central pouring gate 20 which The cope, as in Fig. 1, comprises an integral inner ring 23 and connecting webs 24. A pressure ring 25 fits into the annular space thus formed, and has slots 26 for accommodating the webs, and a renewable bottom 25. The drag 22 is provided with arenewable plate 27 which serves as a base for the sand gate 20. The metal to be cast is poured into the gate 20 and the gases in the mold escape through vents 28 formed in the cope section. lvhen the mold has received the required amount of metal, including an allowance for contraction, it is placed upon a press, and the ram 29 a of the press is started downward. This ram engages the pressure ring-andshears the pin 30 that supports the ring in raised position, forcing the ring downwards upon the molten metal in the rim of the wheel and sealing the vents 28. If the pressure is applied too soon, metal will rise in the gate 20. As will be seen from Fig. 2, the plate of the wheel is the thinnest portion and will, therefore, solidify first. Consequently, if any metal is forced upwards through the gate, it will immediately indicate that the metal in the plate ofthe wheel has not solidified, in which instance the pressure is immediately stopped or more gently applied until the plate of the wheel becomes solid enough to withstand greater pressure. The continuing pressure upon the rimacts to prevent the development of cracks, or stress, such as would inj are the casting.

lrVhen the metal has solidified, the ram of' the press is moved upward. A pair of hooks 29 pivoted to the ram are/adapted to slide under corresponding projections 21 formed on the cope section. The cope section, pressure ring and gate are thus lifted with the ram, the shape of the gate causing the casting to be lifted free of both the cope and drag section, leaving the wheel free to contract without interference and without binding itself to the mold in which it was formed, and is subsequently finished as desired.

Another application of this method of forming standard castings in permanent molds is illustrated'in Figs. 3, 4,5 and 6, which show the apparatus and manner of casting a column guide. An article of this shape cannot be cast in a rigid mold with existing methods owing to the tensile stress developed between the projections 31 and '32 as the metal coolsand contracts. These projections would be held in the mold recesses provided for them which would obstruct the sure into the matrix of themold. The plunger is held in casting position by a pin 36 inserted in a hole in the plunger and bearing on the top of the cope section. A movable plate 37 is adapted to form one side of the matrix and is held in position by wedges 38 adapted to rest on and slide through the cope section 33. The plate 37 is recessed in such a way as to form part of the projections 31 and 32, shown in Fig. 3. A gate 39 made of sand is formed in an extension of the mold, as shown in Fig. 6,

and a gate cutter 40 is inserted in a slot adapted to receive it in the cope section. The cutter is held in position by a pin 41 resting on the top of the cope, and is held in uprlght position by the guides 40'.

When the mold has been completely assembled it is mounted upon a suitable hydraulic press and molten metal is poured in through the gate 39 until the matrix of the mold is entirely filled, the gases escaping through the vents 33. The gate cutter 40 is then forced down shearing off the pin t1 then continuing downward cutting through the metal in the gate 39 and forcing itself into the slot 42,-th11s completely closing the matrix.

Pressure is then applied to the plunger 35 which shears the pin 36 and then transmits the pressure to the metal at all points between the projections 31 and 32, as shown'in plan View in Figure 4. This pressure acts to prevent any cracks or undue tensile stress developing in the casting. lVhen the metal has become substantiallysolid, the pressure is released and the ram on the press moved upwardly. In its upward travel it engages the hooks 38 unlocking the plate 37. The mold side 37 is then Withdrawn by means of a hook 43 attached thereto, allowing the metal cast to contract free of obstruction. The mold and casting are then removed from'the press and the casting taken out of the mold.

Another article to which this method is applicable is a car truck side commonly called a side frame, illustrated in Fig. 7. This side frame is cast in a permanent or rigid metallic mold of which a sectional elevation taken on line 88 of Fig. 7, is shown in Fig. 8, and a cross section on line 99 of Fig. 7, is illustrated in Fig. 9. The matrix of this mold is formed. by mold sections 51 and 52 by a movable plunger 53. The mold' piece 52 is provided with an extension for the formationof a sand gate 51' and a gate cutter 55. The mold is assembled complete and its matrix is thenfilled with metal through the gate 51 I indicated in Fig. 7. It is to be observed that the pressure is applied upon the braces 50,

50", 50 and 50 the natural contraction of cated in Fig. 7 are not obstructed from natural contraction, and, therefore, do not require pressure to prevent tensile stress developing therein, although in this instance pressure would do no harm, because these parts are as thick as some of the other frame members. As the metal cast solidifiesin the matrix, the pressure exerted is maintained,

'thus preventing the existence or development of tensile stress in any portion of the casting up to the moment that the pressure is released. Directly after the metal has substan- 'tially solidified, the pressure is released ,by

starting the press ram in an upward direction. This press ram has hangers pivoted thereto which are adapted to engage hooks 56 and withdraw the mold piece 52, which, in turn, withdraws thecasting and the plunger 53. so that the metal cast-is drawn away from all projections of the mold piece. The metal cast is thus free to. contract without obstruction, and whereas it has already become substantially solid before the release of the pressure, any tensile stress set up in the metal while withdrawing it from the mold will not crack nor injure it provided it have a sufficient elongation, as pointed out in connection with the casting of the tire.

This method will also form cast articles of varied and sudden changes in thickness, free.

from undesirable internal stresses which weaken the casting. An article of this kind is a crane rail bridge, illustrated in Fig. 10.

VVhen this article is cast in either sand molds or rigid molds according to old methods, the base 61 cools and solidifies more rapidly than the body 60 due to its thinner section. The quicker cooling of the base results in a more rapid rate of contraction, whichtends to bend the casting. As bending is prevented by the mold, the reaction of this unequalFrate of contraction causes tension in the base 61, which results in either a cracked or stressed casting. Finally as the thicker body 60 coolsafter the base 61 has become rigid, the contraction of 60 causes the bowing of the casting convex to the base side. In rigid molds (sometimes come in sand molds) this causes fiawing of the casting by excessive shearing stresses between body and base. This condition can be avoided and perfect castings having varying thickncss and rates of contraction can be made by applying to selected regions of the casting a pressure which will serve to hold all those portions of the cast which are delayed in cooling under adequate pressure until they have well solidified thereby counteracting the tension that would otherwise develop therein.

If a rigid mold, as shown in Fig. 11, having a plunger ada ted to press upon the faces 63 and 64, is use the casting while solidifying, will be in compression, allowing the thin sections to solidify as a compact mass and also acting upon the thicker section until it becomes substantially solid. In this manner the heavier, slow cooling parts of the cast are held substantially in compression during their solidification. so that undue stress in the solidified casting is prevented. Similar results may be obtained by applying prcssure to the thick portion only of the casting on the faces 62 and 62'. In fact perfect castings of this self-obstructing type may be made free from undue internal stress, regardless of how the pressure is applied provided the slowcooling portions of the cast are adequately compressed during their solidification and provided the metal cast has the property of sufficient elongation to relieve any injurious stress which may be created by normal contraction in cooling after the casting has become substantially solid.

The process may be applied to form a gearwheel, as shown in Fig. 12. The gear-wheel blank 70, is placed upon the drag section 71 and the cope section 72, locked down upon the blank 70, with the compression ring 7 3 adjusted to the correct position by resting upon the pins 74. The compression ring is tapered in such a manner that when it reaches its full travel under pressure, the volume of the solidifying metal in the matrix 75, will be reduced as indicated by the chaindotted lines 76.

When the matrix has been filled with molten metal and the pouring gate (not shown) is sealed, pressure is applied to the compression ring upon the face 77, shearing oif the pins74; andswedging the solidifying metal radially toward the hub 78, thereby reduring its cross sectional area as it shrinks and contracts during solidification, by continually forcing the compression ring with itsconical interior face downward upon the solidifying metal, until the cast metal is sufliciently solid to acquire sufficient elastic properties to shrink upon the metal gear blank without cracking, flawing or developing undue internal stress.

In Fig. 3 the process is directed to casting an outer ring upon a circular drag section 80, of a wheel-centre mold, so that the drag section is a metal core, causing rigid obstruction placed to form a pouring gate 87. When the mold thus assembled is filled with molten metal, the gate cutter 88, is forced downward, cutting off the gate and sealing the mold, such gasesas may be in the metal cast escaping through the vent holes 79. Immediately thereafter pressure is applied to the compression ring upon the face 89, lateral pressure on the metal cast beingderived from the tapered or conical interior of the compression ring. As the metal solidifies and contracts the compression ring is forced by the pressure to move downwardly and seal the vent holes 7 9 until finally when the metal becomes substantially solid and has acquired sufiicient elasticity to shrink upon the core 80 without flawing or developing undue internal stress, the compression ring 89 by constant travel will have reduced the cross sectional area of the matrix by an amount sufiicient to 'compensate for the contraction of the cast metal during the solidification period, as indicated by the chain dotted line 90.

Another application of this method of applying metal in a solidifying state to rigid articles, that obstruct the normal shrinkage and contraction of the cast metal, is illustrated in Figs. 14, 15, 16, in which a dipper tooth is applied to a metal shank. The numerals 91 and 92 indicate the shank and tooth, while 93 is the mold for forming the dipper tooth and is adapted to closely fit over the shank and slide upon the housing 94. The mold is held in casting position by hinged keys 95 and a refractory gate 96 is inserted through the mold, as shown in Fig. 16. A gate cutter .97 equipped with beveled lugs 98, is

, inserted in grooves in the top of the mold and the shank is held firmly in place by means of the bar 101, which slides under a hook 102. When the ,mold and shank are completely assembled, the whole unit is mounted upon a horizontal hydraulic press and molten metal is poured in through the gate 96, the gases escaping through the vent-holes 93'. lVhen the mold is completely filled, lateral pressure is applied against the gate cutter 97, sealing the mold and forcing the lugs 98 against the hinged keys 95, thereby permitting the mold to be free to slide upon the housing 94. Lateral pressure exerted by the ram of the press is then applied to the face 100 of the mold, which in movement squeezes the 'cast metal inwardly on all sides against the projection 91 of the shank, thereby maintaining the peripheral length of the cast metal around the projection and decreasing the volume of the matrix of the mold as the metal shrinks, contracts and solidifies to prevent the development of injurious stresses by holding the'cast metal under sufficient pressure until it has acquired suffic-ient elasticity and tensile strength to shrink upon the shank without flowing or developing undue in ternal stress.

Still another article that can be produced with this method is a steel back brake shoe illustrated in Fig. 1-7. A cast iron wearing plate 110 is disposed in a permanent mold 111, shown in Fig. 18, which comprises a movable side 112, locked therein by the shank of the hook 112, a plunger 11-3 and a closure top 114. A sand gate 115 is projected from one side of the mold, and a gate cutter 116isinserted through a slot in the mold extension. The cast iron wearing plate is inserted in the mold and has cone-shaped holes 110 adapted to be filled with molten metal and may also be flanged at both ends as at 110 so that the metal will bind itself thereto. Metal is poured into the matrix of the mold through the gate 115, and when the gate is filled it is closed by forcing downward the gate cutter 116 which engages ina recess 117 1n the bottom of the mold. Pressure is then applied to the" plunger 113 and presses the metal in the matrix, preventing any fissures or undue tensile stress developing in the metal cast, and also preventing the shearing or breaking away of the metal projections that fill the cone-shaped holes in the wearing plate, or for breaking awaythe metal which fills the re cesses formed by the flanges at the ends of the back, since the plunger covers the total top area of the casting. Upon solidification of the metal, the pressure is released and the casting removed. As the wearing plate ohstructs the contraction of the metal cast, the

latter will readily elon ate accordin ly and bind itself securely to t e back, but the steel utilized must have the proper elongatlun characteristic, as already pointed out. If pressure had not been applied to the unsolidified metal, the subsequent contraction would cause the metal cast to separate, resulting in cracks and fractures.

The pressure required and the points or I believe it should be well over 500 lbs. per

square inch and, in some cases, I have found upwards of two tons per square inch to be best, but obviously, this will depend upon the characteristic of the metal and the magnitude of the undesirable contraction to be overcome. I believe that suflicient pressure applied in proper direction over selected areas of the casting, compels the flow of the semi-solid metal upon which pressure is brought to bear in such direction as to cause the movement of the metal itself to offset undesirable contraction therein. I desire to apply this pressure in such direction as to hold in a state of compression those portions of the casting which are tending to shrink (against the rigid obstructions) during solidification or to contract after first becoming partially solid. I have observed that during solidification molten steel passes through a succession of so far advanced as to give the metal the necessary tensile strength to produce ductility and allow elongation without fracture. Thus by a sort of sidewise squeeze exerted along one face of the body of metal between two obstructions, I believe the plastic metal within forces or stretches outward and holds in place against the face of the mold, any portions of solidified metal skin and, at the same time, it evenextends the length of the material between the obstruction to a degree substantially equal to its contraction and shrinkage.

I believe that excess pressure doesno harm. I believe it is this flow of shifting of metal which produces a characteristic deformation of shape and reduction of size in the crystals first formed as the metal solidified and which enables me to identify castings thus produced by variations in microcrystalline structure which is somewhat similar to the crystal modification or deformation produced in wrought metal. 1

One advantage of this process of casting 1n rigid molds is that it permits the production of large steel castings in a rapid and system- I atic manner without material wastage or loss at much of molds with practically the same orderly facility as can be applied in the quantityproduction of drop forgings. At the same time by rotation of fresh cold molds under the press all those difficulties are eliminated which have hitherto made it impossible to produce large metal articles direct from molten metal by any process of drop forging or die casting.v

.' I am aware that it has been suggested that pressure be applied to molten metal while it is cooling for the purpose of expelling the gas bubbles or pipes in making ingots, but, in such case, the pressure was not applied 1n a manner to prevent cracks, fissures or undue stresses, which would otherwise occur due to contraction or shrinking of commercial articles or primary products in a mold. With the use of my improvement smooth, sound steel castings of many designs may be formed in rigid molds. Likewise steel articles now made as drop forgings may be cast in a manner to have exterior and interior surfaces equal in finish to the best drop forgings and lower cost. Many other applications of the invention will be apparent to those skilled in the art.

While I have described my improvements in detail in connection with certain forms and applications thereof, I do not desire to be limited to such details and forms since my invention .may be embodied in widely different forms.

What I claim as new and desire to secure by Letters Patent is:

'1. The method of making metal castings wherein the configuration of the casting or the resistance of the mold is such as to normally prevent the casting, from solidifying free of cracks, fissures or undue internal stress, which consists in pouring the metal int-o the mold and applying to the metal in the mold substantially throughout the period of solidification a pressure of such value and duration and over all parts where greatest obstruction to normal contraction occurs, as to prevent the formation of fissures, cracks or undue internal stress.

2. The method of making metal castings wherein the configuration of the casting or the resistance of the mold is such as to normally prevent substantially uniform contraction throughout the article, which consists in pouring the metal in the mold, sealing it and immediately applying pressure to the metal at all parts where normal contraction is obstructed for such timeand in such direction as to aid natural shrinkage and contraction to offset the tendency to form cracks and thereby produce an article free from cracks and undue internal stress.

3. The method of making metal castings free from cracks or undue internal stress in molds that obstruct the normal shrinkage and contraction of the casting, which consists in pouring metal into the mold sealing it and applying pressure exceeding one ton per square inch before solidification is complete of such duration and over such area or areas as to keep in contact all particles of the solidifying metal in substantially all regions of the casting wherecracks or injurious stresses would otherwise develop, substantially throughout the period of solidification.

4. The process of forming castings in sealed rigid molds that obstruct the natural shrinkage and contraction of unsolidified metal cast therein, which consists in applying pressure upon all outer portions where shrinkage is rigidly obstructed in a suilicient amount to cause the solidifying metal to flow in the direction of-natural shrinkage and contraction substantially throughout the period of solidification.

5. The process of controlling the shrinkage of castings while solidifying in rigid molds, which consists in compressing all parts where greatest obstruction to natural contraction occurs bydirectly applying pressure of suflicient intensity and duration to the metal on said parts as it passes successively through the fluid, the pasty or granular and the soft plastic states, as to cause compression in all parts of the casting which cannot freely shrink until such parts have solidified.

6. The process of directing the shrinkage of solidifying metal in rigid molds, which consists in maintaining pressure upon all outer parts of the cast that are obstructed from normally shrinking, of suflicient intensity and duration as to decrease the volume of such outer portions as they contract and force metal to flow therefrom into other parts of the casting in a direction that shrink age and contraction would normally occur during the solidification of those parts wherein shrinkage is to be directed.

7. The process of producing castings which consists in applying pressure to all parts that cannot normally contract without flawing in such a manner as to aid natural shrinkage and contraction and decrease non-essential dimensions and maintain the essential dimensions along the line of which the metal would otherwise be detrimentally affected by the strains created in shrinkage and contraction.

S. The method of making castings of metal in molds having a rigid obstruction to shrinkage of the metal in cooling, which consists in applying pressure upon all parts where greatest obstruction to natural contraction occurs to compress the solidifying metal where its shrinkage is rigidly obstructed for sufficient time as'to prevent the formation of material cracks or flaws in the casting due to shrinking.

9. The process of making metal castings in sealed molds. having rigid obstructions to the shrinkage, of the solidifying metal confined therein which consists in applying upon all regions where great obstruction to normal contraction exists in said castings before solidfiication is complete, sufficient pressure to create compression in substantially all regions of the said castings that are obstructed from shrinking. throughout the latter stages of their solidification, and the maintenance of such pressure. until said ohstructed regions acquire sufficient elasticity, as to shrink upon rigid objects without cracking or fiawing.

10. The method of preventing the development of cracks during the solidification of cast metal articles in rigid molds which comprises the application and maintenance of,

sufficient pressure upon all obstructed parts of the cast where greater shrinkage and contraction would normally occur to cause such a movement of the metal in the direction of the resultant of the contracting forces, as to prevent the formation of cracks or undue internal stress.

11. The method of preventing the development of cracks or undue internal stress in solidifying metal castings in rigid metal molds, which comprises the direct compression of substantially all outer regions where injurious tensile stress would develop if the casting were allowed to contract naturally, and holding such regions in a state of compression until the casting has substantially solidified.

12. The method of making a metal casting free from cracks or injurious internal stress in a mold that rigidlyobstructs part of the casting from naturally shrinking and contracting, which consists in applying to outer parts obstructed from normally contracting -a pressure of suflicient intensity and duration as to cause a movement of metal out of such obstructed parts, into other parts of the casting in the general direction of natural shrinkage and contraction.

13. The method of making metal castings in molds having rigid obstructions to the natural shrinkage and contraction of a part of the metal therein, which consists in pouring metal into the mold, sealing it and applying before solidification is complete to all parts where greatest obstruction to contraction would normally occur, sufficient pressure to create compression in said obstructed parts to a greater extent than in other parts of the metal, cast throughout the latter stage of solidification and the maintenance of such pressure until said obstructed parts have acquired elastic properties.

14. The method of shaping solidifying metal in rigid metal molds that obstruct the shrinkage of the said metal, which comprises the substantial closure of the mold directly after pouring, and immediately thereafter to compensate for the normal decrease in volume, caused by contraction in three dimensions during cooling, as well as to prevent the development of destructive tensile stress in any part of the casting when it has solidified.

15. The process of forming flawless cast ingsin molds having rigid obstructions to the shrinkage of the metal cast therein, which comprises the application of pressure through selected movable parts of a sealed mold acting upon all parts where greatest obstruction to natural contraction occurs that is sufficient to cause solidifying metal to flow where shrinkage is obstructed, said pressure to be released only when obstructed parts are sufliciently solid to resist strains caused by the further prevention of shrinkage without cracking.

16. The method of utilizing permanent or rigid molds with cores which comprises the substantial sealing of the mold after pouring the casting, the application of pressure by movable portions of the mold to all points where greatest obstruction to natural shrinkage and contraction exists and the increase of said pressure as solidification proceeds to cause fiow of the solidifying metal and cause movement of the metal under pressure into other parts thereof in the direction of natural contraction to eliminate injurious tensile stresses due to shrinkage and contraction during solidification.

17. The process of making wrought castings in molds having rigid obstruction to the shrinkage of the metal, which consists in pouring the molten metal into the mold, substantially sealing the metal in the mold, and applyin pressure through a movable part of the mold upon all parts where greatest obstruction to normal contraction exists holding said obstructed metal in compression, by maintaining pressure application until the obstructed metal has sufficiently solidified to resist shrinkage without the production of cracks or flaws.

18. A new article of manufacture, a cast steel wheel exhibiting in the rim and tread thereof a more compact microscopic granular structure, than in other parts thereof, and a varying degree of deformation and destruction of the natural microcrystalline structure of the metal throughout the casting.

19. The process of casting metal in a permanent mold onto a rigid article that rigidly obstructs the normal shrinkage. of the cast metal, which consists in causing the volume of the matrix of the mold to be greater at all regions where the natural contraction of the metal cast therein is obstructed, and the selective application throughout the period of solidification by movable parts of the mold of a swedging pressure to these regions adapted to decrease the volume of the matrix at said regions of obstruction by an amount substantially equal to the decrease in volume of the metal cast when changing from a liquidzto a solid state.

20. The method of making a cast-bound metal article wherein the article bound would normally prevent the cast metal from solidifylng free from cracks, which consists in pouring metal around a rigid article in a mold, sealing the mold and then applying to selected areas of the cast metal a pressure sufficient to keep in contact all particles of the solidifying metal until the metal becomes substantially solid and self-sustaining.

21. A process of applying unsolidified metal to a rigid metal article that obstructs its natural shrinkage, which comprises urging solidifying metal by selective application of a swedging pressure into those regions where the natural shrinkage is obstructed.

22. A method of casting metal around a circular object that obstructs it from normally shrinking and contracting, which comprises the application of pressure exceeding one ton per square inch to one face of the cast metal during solidification, said pressure being maintained until the natural shrinkage of the rim in peripheral length has been compensated by reduction of its solid cross section. 23. The method of casting metal onto rigid objects of such configuration that they revent the cast metal from normally solidifying free of cracks, fissures or undue internal i stress, which consists in placing the objects in rigidmolds, filling the molds with molten metal and applying to the solidifying metal a pressure of such value and duration and over such area or areas as to prevent the formation of fissures, cracks or undue internal stress in the cast metal during its solidification.

24;. The method of applying unsolidified metal to rigid articles, which consists in pouring metal into a rigid mold, in such form as to overlap or grip the said article and immediately thereafter applying to the solidifying metal, a pressure upon obstructed portions thereof of such value and duration as to prevent the formation of cracks or undue internal stress substantially throughout solidificasubstantially throughout solidification, saidpressure being maint-ained until the natural shrinkage of the tire in peripheral length has been compensated by the reduction of its solid cross section.

26. A cast-steel tired wheel, exhibiting in cross section a rough metal wheel center elastically bound by a sound cast-steel tire, said tire closely fitting into any irregularities in the contour of the rough wheel center and exhibiting a morecompact microscopic granular structure than ordinary cast-steel of similar analysis and a varying degree of deformation and destruction of the natural microcrystalline structure of the metal throughout the tire.

CERROL E. REINHARDT.

CERTIFICATE OF CORRECTION.

Patent No. 1,699,120. I Granted January 15, 1929, to

CERRQL E. It is hereby certified that error appears in the printed'specification of the above numbered patentrequiring correction as follows: Page 1, line 14, after the period following the word "stress" insert "The invention is particularly -applicable to castings of soft iron and steeL"; and that the said Letters Patent should he read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 19th day of February, A. D. 1929.

M- J. Moore, (Seal) v Acting Commissioner of Patents.

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