US1819942A - Method of casting continuous polygonal bands - Google Patents

Description

Agg..18,1931. w. M. CARTY 1,819,942

nunon or cAs'rInG CONTINUOUS Powuoxm. nuns Filed Feb. 20. 1929 q A By s L Attorney Patented Aug. 18, 1931 nears. rATEs PATENT OFFICE] WILLIAM M. CART'Y, OF PINE BLUFF, ARKANSAS, ASSIGNOR 0F ONE-THIRD T0 EDWIN J. KERWIN, OF PINE BLUFF, ARKANSAS, AND\TWO-TIIIRDS TO STANDARD BRAKE SHOE & FOUNDRY CO., OF PINE BLUFF, ARKANSAS, A COPARTNERSHIP CONSISTING OF FRED L. DILLEY AND EDWARD S. DILLEY METHOD OF CASTING CONTINUOUS POLYGONAL BANDSl Application filed February 20, 1929. Serial No. 341,469.

This invention relates to a method of casting metal bands and more particularly to a method of casting continuous polygonal steel bands.

One of the objects of the invention is to provide a method of casting steel bands which will prevent cracking of metal during the solidification from molten to the solid state.

Another object of the invention is to provide a corner structure of the mold used in casting the continuous band which will counteract the strain set up at angular portions of the band.

Further objects cf the invention are to provide a cheap and economic means which does not require the use of special equipment and which may be used by unskilled labor, that requires a minimum of parts to be used'in the method and is particularly adapted to methods of foundry practice.

lith the foregoing and other objects in view, the invention consists of the novel construction, combination and arrangement of the casting mold more specifically described and illustrated in the accompanying drawings wherein is shown an adaptation of the mold through the process of casting,

but it is to be understood that changes, variations and modifications may be resorted to which fall within the scope of the claim hereto appended.

In the drawings wherein like reference characters denote corresponding parts `throughout the several views,

Figure 1 is a top plan view of the mold in assembled condition, ready to receive the molten metal, and having the sand removed flush with the top of the mold cavity,

Figure 2 is a central longitudinal sectional view through the mold showing the casting in the mold after it has been formed,

Figure 3 is a perspective view of the iinished continuous band, in accordance with this invention, I

Figure 4 is a fragmentary side elevation illustrating the position of the corner chill with respect to the corner of the finished casting in accordance with this invention.

lIt has been the custom to take two U-shaped sections and either form them by welding in the blacksmiths shop or by forging .them under a hammer. This method of making a continuous band is not only cumbersome `and expensive `but the finished band has all of the weaknesses attending welding and forging. The strength at thev weld or forged seam is materially less than the tensile strength of the other portions of the band and it has been found in pracf tice that such bands will break ing conditions.

To providea forged or Welded band it is always necessary to use material of greatunder worker strength so as to compensate for the weaknesses set up aty the forged or welded portions of the band. difficult to cast polygonal continuous vbands because of the surface crack and incipient strains set up upon cooling of the casting.

It has been found from experience that the cracks and incipient strains occur at the corners of the continuous band. To overcome the aforementionedV difficulty the method of casting a continuous polygonal More sand is then thrown into the mold and packed firmly until the pattern is covered by the sand. The pattern is then withdrawn and the outer wall of the mold is thereby formed, 'leaving a space internally thereof for the reception of the core C. The

foregoing description serves the purpose of explaining this invention,v but it is within the contemplation to lform the mold in accordance with regular foundry practice.

In the regular foundry practice the flask is in two sections and the pattern is in one section representing the exact design of the band. The continuous polygonal band is made from a one piece pattern lying all in Heretofore it has beenv the drag half of the mold. `When each section of the flask is complete and the pattern section withdrawn the said sections commonly known as the cope and drag are `then disposed u pon each other and forni the complete mold as is shown in Figure 2 of the drawings.

Having formed `the outer wal-l ofthe mold as indicated at 6, and there being a hollow depression interiorly of the outer wall 6, the mold is then assembled or fit-up in accordance with the following description. The core C having first been formed, as will hereinafter be described, is placed interiorly of the outer wall 6 having the faces thereof parallel and spaced with respect to the outer wall 6 of the' moldrlhecore ,is provided with in-set right angled shoulders 7-8 at each-,of the corners thereof; At the `center of the lcore is an opening 9 extending transversely l thiroug-h the core and adjacent the opening the core is provided with a circular wall 10v that forms the opposite side faces of said opening.

The side faces l() are positioned lon-gitudinally of the longest dimension of the core, while onthe` faces oppositethe shortest .dimension of the core are provided .plane surfaces 11. The distance from the outer faces of the core C and the inner'wall 10 less than the .distance from the plane faces 11 to theouter faces of the said core.

VThe latter construction gives greater re-V core completes the interior wall of the mold providing a space between the outer wall 6 andthe assembled core C in which the molten metal is received and retained until it solidifies. rlhe chill member 12 in addition to having two faces abutting against the inset faces 7, 8 of the core, is anchored in the sand S as 'indicated at 14 so that it will have additional support in the bottom layer of sand. i

The chill member is cut ofi'l flush with the top of the cores C so as not to interfere with the fitting up of the flask preparatory to pouring the same, That portion of the chill member 12, which projects into the bottom layer of sand as at`14, .also serves as a projection to receive 'blows of a hammer when the said chills are knocked off after the casting is complete.

Leading' from the top surface of the sand 15 is funnel shaped opening 16 through which the molten steel is poured into the space formed between the sand wall 6 andthe core C. This funnel shaped opening is of materially greater area` .than the width of the walls of the casting and thereby contains enough of the molten metal to supply the casting with metal during its solidilication.

The funnel shaped portion 16 is known in the field industry as a gate or riser and when severed from the finished casting usually-leaves a rough surface as indicated at 1r.

The outer wall 6 is formed of sand coni- -posedof burnt or used sand, new silica sand, clay, a small proportion of bentonite and molasses water to form a binder, a propor- .tion of which are well known' to the steel industry.

The composition of the core C is part clay, of a higher proportion than the outer wall 6, bentonite, charcoal, silica sand and any of the well known commercial vbinders which-are well known to the foundry art.

'The chill menrber 12 is made of gray iron or ,steel and will not be fused with the moltenl steel other than sticking'to the inner wall of the casting. lt is pointed out that while ,the chill member 12 adheres-to the casting it may be knocked from the same by the ,ordinary lblow from a lsledge hammer.

The outer wall formed of sand composition as at 6, is resilient to the expansion of the metal Vat all temperatures from the liquid state .to the solid state. The resilient walls compress equally in a rearward direction toward, the flask 5 but .the said wall 6 will not vbe frangible during the solidiication of the casting. The core member C having been formed with a hollow center is .of such consistency that it will retain its shape but it will be resilient to the expansion of the metal from theA molten or yliquid state down to 4temperaiuires and pressures of the setting or plastic stage of the metal casting.

Below plastic or setting stage metal, the spa-nd .portions kof the core will be frangible and crank through strains of shringage. The chilled .members 12 at the corners of the sand Vcore C are rigid and will not be distorted by the angles of thercasting but the chills 12 are flexible ,enough to allow shrinkage of the casting.

It is furthermore pointed out that the chilled A-inembe-rs 12 being of metal as distinct from the core C have a tendency'to chill the casting quickly at the corners whereas in the area around the core and adjacent to the corners is a high resiliency imparted by the zouter sand wall 6, and the sand portion yof the cores C. The core and sand walls will permit cooling of the casting more slowly than the chills.

While there are certain strains in the Vmetal due .to the chill construction of the corners of the core it has been found by experiment that checks and cracks are entirely eliminated by the chill corners of the core. The aforementioned stra-ins are overcome by heat treating the finished casting after it has been knocked out of the mold.

Having performed the mold in accordance with the foregoing description the same is ready for the pouring operation. In the assembled condition the space 18 between the outer wall 6 of the core C is filled with liquid or molten steel of such composition as will be hereafter described.

The molten steel is poured down through the funnel shaped head 16 which registers with the space 18 and when the space 18 is filled the head 16 is poured full of metal flush with the top of the mold 15. The head 16 feeds the metal in the space 18 and compensates for contraction of the metal during the solidification. f

This contraction is entirely different and unrelated to the shrinkage and is what is known in the steel industry as piping or a depression formed at the upper surfaces of casting. By supplying an excess of metal the depressions are fed and made solid. By referring to Figure 2 of the drawings the walls, the hollow core, and the casting is shown after it has been poured, and the casting 19 in the space previously designated at 18.

It is pointed out that the rounded corners of the chill 13 materially aid in reducing the strain at the angular corners of the casting. r

It is within the contemplation of this invention to cast a one-piece continuous polygonal band of low carbon steel ranging from .15 per cent to .25 per centqwith the usual manganese, sulphur, phosphorus consistent with the low carbon steel.

Itis pointed out that it is possible to cast alloy steel bands with this method. The physical properties of this finished steel runs from sixty thousand to seventy thousand pounds per square inch tensile strength, twenty-seven thousand to thirty-five thousand pounds per square inch elastic limit and around 2 per cent elongation.

The advantages of the method of casting this continuous band 15 manifest when one considers that the ordinarily forged or welded band has a tensile strength of only one-half the band made in accordance with this invention. 'Ihe band prepared in accordance with this invention has many applications in the industrial art, but it is particularly adapted as a confining member wherever strength and ductility are required.

Its greatest use is in the railway equipment art, as a confining member for the leaf spring on locomotives, tenders, boX bars and the like. In the application of the invention, a layer of sand is placed in the bottom of the flask 5, the pattern is then disposed on top of the first laye-r of sand, and themold. is then filled the remaining distance with the sand.

The pattern being solid leaves an opening centrally of the flask and interiorly ofthe outer wall 6. The chills 12 are then anchored inthe bottom layer of sand Aand the core member C is inserted in the opening loft by the removal of the pattern.

' The chills are adjusted so as to fit in the angular corners of the mold C and the head and is formed so that its narrow bottom registers with the space between the outer wall 6 and the core C. The molten steel is then poured down the head 16 until the metal rises to the top of the surface 15 thereby insuring that the space 18 has ben filled with metal.

The excess metal in the Vhead C which forms no part of the casting, feeds surface contraction and overcomes the piping at the Vupper faces of the casting.` The outer wall 6 being of a sand composition is resilient to the strain set up by the solidification of the casting. The inner core being hollow. adjacent its outer faces is strong enough to stand expansion of the metal from the liquid to the plastic stage, below the plastic stage, the walls of the core are cracked thereby making a frangible core at temperatures below the setting stage.

The corners are rigid and prevent any movement at or near the corner, while at the same time the body portions thereof cause the metal at the angles of the band to solidifyV more quickly than substantially elongated portions of the band.

The rigidness with the quick chilling of the metal of the casting prevents cracks, checks or internal strain. After the casting -has set until after it has lost its red hot color, the same may be knocked out of the mold and the solid head may be removed in any of the customary ways known to the art.

It is possible that the chill members 12 adhere to the removed casting and they may be knocked loose by a blow from an ordinary sledge hammer. When the casting has been removed from the mold, it is placed in a heating furnace, the temperature thereof is brought up to a. point within its critical range, which in this class of steel is from 157 5 degrees to 167 5 degrees Fahrenheit. The temperature o f the castings are so held at the critical range that the crystals of the steel become homogenous whereby the internal strain caused by heterogenous crystallization is relieved.

In heat treatment or normalizing, the furnace is cooled below the critical range and the casting may be removed and air cooled or may be allowed to remain in the furnace to impart a greater ductility.

Having thus described my invention, what I claim as new is:

The process of casting a continuous polygonal metal band comprising pouring molten metal in a mold cavity, subjecting the corners of the metal to a" rigid supporting and chlling'aetion, and subjecting the baizmce of the metal to ,a restricted'expanding action While the metal is cooling to the se1fsupporting stage and to a contracting action after the metal reaches the self-supporting stage.

In testimony whereof I aflix my signature.

WILLIAA M. CARTY.

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