US2431879A - Apparatus for casting steel rolls - Google Patents

Description

Dec. 2, 194.7. E. H. MEBS APPARATUS FOR CASTING STEEL ROLLS Filed May 22, 1945 2 Sheets-Sheet 1 O 4 l h xx m O O O O O O D O Dec. 2, 1947. ME s APPARATUS FOR CASTING STEEL ROLLS Filed llay 22, 1945 2 Sheets-Sheet 2 Inventor 4y few/N M555.

' an enlarged diameter,

of smaller diameter, and an upper neck portion 55 per cup 42 having a Patented Dec. 2, 1947 Erwin H. Mebs, Johnstown, Pa., assignor to Carg negle-Iiiinois Steel Corporation, a ighfiv nib w, lira-w we of New Jersey c i T J. h J

Application May 22, 1945, Serial No. 595,091

. 1 Claim. 1 The present invention relates to an improved method and apparatus for casting ferrous metal objects while in vertical upright position.

' manner that there is provided during the casting operation a localized plane of weakness in a predetermined plane whereby if breakage or cleavage takes place during the solidification of the casting, it will occur at or closely adjacent to said predetermined plane of weakness.

A further object of the invention is to provide a method of casting ferrous metal objects in such manner that during solidification of the metal a zone of weakness is maintained at a predetermined plane below the fluid metal so as to localize the tendency to form hot tears at said localized zone of weakness.

For a more complete understanding of the invention, reference should be made to the folit of a diameter smaller than the portion l4. In casting such articles in upright position, a problem occurs which is occasioned by the tendency of drastic chilling action to cause the formation of hot tears in the upper region of the article. As will appear more fully hereinafter, under my invention I provide a method and means wherein a zone of weakness is provided such as indicated at in Figure 4, above the upper end of the casting ultimately produced. Above this zone of weakness in the formation of the casting there is produced a portion indicated at 22 which is normally cropped oil and discarded.

In the practice of the invention. the mold for producing rolling mill rolls or pinions is provided with an intermediate mold cavity 24 of relatively large diameter which at the bottom opens into a lowing detailed disclosure, the accompanying drawings, and the appended claim.

.In the drawings:

Figure 1' is a longitudinal section through a novel form of apparatus for carrying out the herein claimed method.

Figure 2 is a cross section on line II-II of Figure 1.

Figure 3 is a cross section on line III-III of Figure 1.

Figure 4 is an elevational view of a mill rolling a body of mold material therein such as high- 1y bonded silica sand, indicated at l2, the mold cavities being formed either by the use of a conventional split pattern or by the conventional sweep method. I

While not limited thereto, the present invention is well suited for the casting of iron or steel rolling mill rolls or heavy pinions. By way of example, I have shown in Figure 4 a rolling mill roll having an intermediate roll portion i4 oi as lower neck portion i4 cavity of smaller diameter. indicated at 28, and

which at the top opens into a cavity of smaller diameter 28, Surrounding the intermediate cavity 24 of large diameter I provide a plurality of metal rings 30 which serve to chill the molten metal during the casting operation.

Above the upper cavity 28 I provide a riser cavity 32. It is apparent from the drawings that the cavities 2B and 2. correspond to the lower and upper reduced diameter neck portions i8 and it of the roll, shown in Figure 4, and that the'cavity 24 corresponds to the roll body portion ll of enlarged diameter of Figure 4. Similarly, the riser portion 32 of the mold corresponds to the portion 22 of Figure 4.

A particular and essential feature of the herein claimed invention relates to the method and means for creating the zone of weakness in the article durin the casting thereof. This is accomplished by incorporating in the mold means such as indicated at 34, for forming a restricted orifice 38 in a predetermined plane between the upper mold'cavity 28 and the riser cavity 32. The means may be in the nature of a disc or slab of any material of sumcient strength and refractorlness, seated in an annular groove or trench 88 formed in the mold. The disc-like member 34 may be made of kiln-dried fire clay either in a single disc-like perforated piece. or it may be formed of a plurality oi arcuate segments. The means 34 which provides the restricted orifice fits in a trench ll, is held in place by the sand, and projects a definite predetermined distance (marked X) inwardly into the region between the mold cavity 28 and the riser cavity 22.

The mold is formed with an upright vertical gate 40, and at the top is equi d with a runi'lared opening 44 into 3 which the molten metal is teemed from a suitable ladle. As best shown in Figure 3, the bottom of the gate has a laterally extending portion 46 which connects tangentially with the lower mold.

cavity 26. In casting rolls or pinions according to the mold cavity 26 is filled approximately tothe level of the tangential entrance 46. Thereupon the pouring ladle nozzle is opened wide and the full stream is permitted to enter the mold through the gate. The metal first rises through the lower cavity 26 and the intermediate cavity 28 in the mold with a spinning motion due to the tangential entry. Any dirt or foreign matter picked up by the stream of rising molten metal is retained in the center of the mold due to the cupping effect and centripetal action, the dirt or foreign matter being lighter than the metal. As the top surface of molten metal rising within the mold approaches the means 34 incorporated in the mold, the spinning action is materially decreased. Therefore when 1 the metal rises through the restricted orifice 36 over the means 34 and proceeds to fill the riser cavity 32,. advantageously there is very little action due to trapped air and no formation of vacuum.

Immediately following the pouring of the mold,

steps are preferably taken to keep the metal in.

the riser cavity 32 molten so that there will be a sufflcient storage of liquid metal for a considerable period of time, to'feed the casting metal properly. This may be accomplished by covway of the riser portion or by the addition of extra hot molten metal at frequent intervals.

A problem overcome by the invention is the prevention of hot tears such as frequently occur in the top parts of large articles cast in vertical upright position. In such' upright cast articles there is always danger of cracks or hot tears forming atthe stage when the metal is at the tender condition known to occur at a temperature of approximately 2350 F. -Heretofore hot tearing has been particularly noticeable in the region corresponding to the upper roll neck It of Figure 4. It is believed to be caused by some sort of holding action within the mold, and I have determined that when castings of this kind solidify in vertical position there is a very considerable linear contraction amounting to as much as of an inch per foot. The metal must be free to shrink. If the gate at the bottom or a fin at'the top holds the metal as it solidifies at such locations, the casting is not permitted to contract freely as it freezes and therenite predetermined zone of weakness in the region of the said means 34 having the restricted orifice 36 therein. By holding the metal during the solidification I refer to the restraint of the natural contraction caused by adhesion of the casting surface to the surrounding compacted sand of the mold. Such restraint or holding of the metal is accentuated by the chills which cause a very rapid cooling and rapid contraction of one portion of the casting while another portion thereof is'in a semi-plastic state. This holding action is particularly noticeable where said semi-plastic portion is of reduced crosssection. It is clear, therefore, that the invention provides for confining the region of hot tearing to a definite and predetermined zone,

thus insuring that the working parts of the casting are thoroughly sound and homogeneous. The

creation of the zone of weakness has the added a bonded sand body and chill members, said sand body having an upright-cylindrical cavity of relatively large diameter in which the roll body is formed, top and bottom cavities of smaller diameter at the ends of said first named cavityin which the roll necks and stock for the wobbiers are formed. said top cavity being of uniform diameter, a tangential gate passage for introducing molten metal to said bottom cavity, anda riser above said top cavity, said chill members being embedded in said sand body around said first named cavity,. a device for localizing hot tears in a casting formed in the mold to a region outside the casting proper-between said top cavity and said riser, said device comprising a transverse ring supported in said sand body between said top cavity and said riser and projecting a fore it is amenable to the formation of hot tears.

invention, the chill within the mold serves as a means for holding the metal during solidification, and in conjunction with thering-like disc 34 restricts the formation of hot tears to a dellpredetermined distance into the mold cavity, the 3 distance of projection of said ring providing a diameter opening through the ring only slightly less than the diameter of said top cavity, whereby said ring creates a plane of weakness between the casting proper and the riser but does not stop flow of foreign material into the riser.

ERWIN H. MEBS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS OTHER REFERENCES Metal Industry, December 27, 1946, pages 533 and 534.

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