US 1747223 A
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Description (OCR text may contain errors)
Feb. 18, 1930.
D. J. CAMPBELL CASTING AND CHILLING MOLD Filed Jan. 17 1927 3 Sheets-Sheet 1 Donok) J. GampM Feb. 18, 1930. D. J. CAMPBELL 1,747,223
CASTING AND CHILLING MOLD Fil n- 1 192 3 Sheets-Sheet 2 ---l W UMW' Z7 r- K 2 26 u 26 .5
F b 4 Donodd 5. GampM Feb. 18, 1930. D. J; CAMPBELL 1 747323 CASTING AND CHILLING MOLD Filed Jan. 17, 1927 5 Sheets-Sheet 5 Patented Feb. 18, 1930 PATENT; GFFEQE DONALD J. CAMPBELL, OF MUSKEGON HEIGHTS, MICHIGAN CASTING AND GHILLING MOLD Application filed January 17, 1927.
This invention relates to improvements in casting and chilling molds. The invention is particularly adapted for casting cam shafts for internal combustion engines and for chilling the surfaces of the cams and bearings thereon, although analogous devices may be cast and chilled by the same invention.
Cam shafts have previously been customarily made of steel and after having been formed the cam and bearing surfaces have been hardened by a heat treating process.
This process would almost invariably result in a warping of the shaft so that it was necessary to submit it to a final grinding and truing operation to make it perfect. This method of construction has been very expensive. The forming of the shaft with its cams from steel, in the first place, is an expensive operation. Then the hardening by heat treating added to the expense, and the necessity of a final operation to correct the defects due to warping from the heat treating process added still more expense.
It has been found, by the use of this invention, that a cam shaft may be made of a good grade of cast iron or semisteel, and may be cast so perfectly and its cam and bearing surfaces chilled and thereby hardened so that it is necessary only to finish the cam and bearing surfaces by a grinding operation to produce a finished and perfect cam shaft.
By use of the mold, including chills embodying this invention, the cam shaft may be cast very nearly its accurate shape and size and inasmuch as the chilling of the metal hardens it for a considerable depth, it is possible to grind the hardened surfaces sufficiently to reduce them to accurate size and shape and not go beneath the hardened part of the casting. The act of molding and chilling the casting simultaneously forms and hardens it and thereby by a single operation produces what formerly required several operations to produce. The operation of molding and chilling is more simple than the operation of forming the shaft of steel and the material used is less expensive. The remaining grinding operation would be approximately the same in either method.
This invention provides a molding flask in Serial No. 161,490.
which the chills for forming and chilling the surfaces to be hardened are secured although means are provided for removing or replacing the chills in case of wear or breakage or for change in the shape of the casting. Allowance is made for contraction of the iron in cooling so that the shape of the casting will not be distorted thereby and various other novel features of construction and arrangement are provided, as hereinafter more fully described and particularly pointed out in the claims, reference being had to the accompanying drawings in which:
Fig. l is a longitudinal sectional elevation of a mold embodying this invention.
Fig. 2 is a horizontal sectional view of the same.
Fig. 3 is an enlarged transverse sectional elevation on the line 33 of Fig. 1.
Fig. 4 is a fragmentary longitudinal sectional elevation of a portion of the flask and chills on the line 4-4 of Fig. 3.
Fig. 5 is a perspective view of one end of one part of the flask, and
Fig. 6 is a perspective view of some of the chills and a portion of the retaining bar in disassembled position.
Like numbers refer to like parts in all of the figures.
The device embodying this invention includes a flask with chills secured therein. The flask is made of two parts which may be called the drag 1 and the cope 2. As shown by the drawings and as preferably made the flask is arranged to contain a mold for the casting of two cam shafts 3 arranged in parallel spaced apart relation. The two mem bers of the flask are accurately located relative to each other by means of the customary guide pins 4 arranged at the respective ends of the flask, the pins being fixed to one portion of the flask and entering holes in the other portion of the flask. The pattern is split at its axial center, thereby molding one half of the pattern in each respective drag and cope portion of the mold.
The cam shaft to be cast is an elongated body having concentric bearings 5, 6 and 7 at its respective ends and middle and a flange 8 of greater diameter than the bearings is located at one end of the shaft adjacent the bearing 7, an annular groove preferably being provided between the flange and bearing. At intervals in the length of the shaft the cams 3 are located. The cam shaft, cams, bearings and flange are all cast integral. The cam surfaces and bearing surfaces are to be hardened by the chilling process.
Each flask portion is provided with a plurality of metal chills extending transversely across it, the chills being equal in number to the surfaces to be hardened and each chill having a surface corresponding to the shape of that part of the pattern which engages it. The chills 9 10 and 11 form the bearing surfaces of the mold while the chills 12 form the cam surfaces. Each chill is cut away at its parts between the molding and chilling sur faces to provide space for the molding sand and also passages for the gates.
Each of the flask portions has a longitudinal depression 13 on each of its respective inner longitudinal sides in which the respective ends of the chills are located, and retaining bars 14, each having a plurality of notches 15 are provided, one being located in each depression with the notches embracing the respective ends of the chills and retaining them in place The retaining members 14 are held in place by bolts 16.
The bearing chill 11 has a ridge 17 which forms the annular groove between the flange 8 and the bearing 7. \Vhen the cam shaft is cast and the usual shrinkage occurs upon cooling the cam shaft is permitted to slide longitudinally in all of the chills excepting the end chill 11 on which the ridge 17 is provided. To accommodate this shrinkage this end chill 11 is mounted for slidable movement in the flask. The respective ends of the chill 11 are provided with pins 18 which enter slots 19 in the flask and the notch 20 in each retainer 14 which embraces the end chill is wider than the thickness of the chill so that movement is permitted. When the mold is made the end chill 11 is moved to its extreme position toward its adjacent end of the flask so that contraction or shrinkage of the metal after the cam shaft has been cast will move the end chill l1 sufliciently to accommodate such shrinkage without distorting or fracturing the casting.
The central chill 10 has flanges 10 at its respective ends in which are tapped holes to receive cap screws 21 which pass through the respective sides of the flask. By this manner of fastening the central bearing chill serves as a stiffening member for the wall of the flask between its ends and thereby prevents spreading of the walls and possibly breakage of them when the sand is squeezed into the flask. The chills extending from side to side of the flask also serve the function of flask bars to aid in retaining the sand in the flask.
All of the chills with the exception of the central bearing chill are retained in place between the retaining bars ll and when it is necessary to change the chills in the flask for any reason, such as to replace broken or distorted chills or to insert a new set for molding a different cam shaft, it is only necessary to remove the bolts 16 and the retaining bars 14L thereby releasing all of the chills excepting the central bearing chill which may be easily removed by taking out the cap screws 21 at its respective ends. If the new set of chills consist of a different number of chills which are differently spaced new retaining bars 14 are provided which will properly arrange them in the flask.
To prevent the formation of gas in pockets in the high cavities in the mold and thereby producing blow holes in the casting the central bearing chills are each provided with relief vents comprising a plurality of fine openings 22 extending through the face of the chill into a larger opening 23 which communicates with the sand. The openings 22 are too small to permit the sand particles to enter them but allow the escape of gas into the larger passage where it will find an outlet through the relatively porous sand. These relief vents are not necessary on the narrower cam chills because the surfaces are not sufiiciently wide to permit an accumulating of gas.
The iron is poured into the mold through a pouring sprue 2d at one end of the cope portion, a so-called runner box 24"' being set on top of the mold into which the metal is poured to enter the pouring sprue. From this pouring sprue it passes through a strainer core 25 and thence branches into three longitudinal gates 26 one of which extends along each outer edge of the mold at its parting and the other extends between the two cam shafts. Each of the gates has lateral sprues 27 joining the cam shafts between the cams thereon. The central gate branches to a pair of risers 28, one of which is located opposite the end of each cam shaft and is connected therewith by a sprue 29.
WVhen the metal is poured the mold is elevated at the end where the risers 28 are located and the iron is poured into the sprue .24 until the mold is filled and the metal rises into the riser 28. During this process steam and gas formed in the mold rises ahead of the metal and finds outlet through the risers 28 at the high end of the mold. Any of the gas which tends'to accumulate in the bearing spaces finds an outlet through the relief vents 22 and 23 and thereby permits the metal to completely fill the mold. When the casting cools and shrinks it will slide in all of the chills except the end bearing chill 11 which is permitted to move as previously described.
By using this flask with the chills secured in it the work of molding is made much more rapid and more accurate. The pattern is made in halves, being divided at the axis of the cam shafts and each half mounted on a pattern plate. The pattern plate is provided with suitable means for accurately locating a half of the flask upon it so that the chills in the flask will properly register with the pattern. The sand is then placed in the mold and jolted and squeezed, this work preferably being done by means of a molding machine. lVhen both halves have been filled they are placed together and accurately located relative to each other by the guide pins 4 which completes the formation of the mold. The gates and spruce having been formed as a part of the pattern and the risers and pourin sprues molded in the usual way.
The chills are made of cast iron or other metal of high heat conducting capacity, so that the molten metal contacting them will be rapidly cooled and thereby hardened, while the parts molded by the sand portions of the mold will cool more slowly and will be relatively soft.
By this method there are no loose chills to be separately inserted and the possibility of inaccurate placement is eliminated. The resulting casting is very accurate in dimensions and shape and requires only a single grinding operation to finish it. Cam shafts made by this process are sufficiently strong to carry out their functions and the surfaces hardened by the chilling process are equal in quality to those produced of steel by the old method.
1. A molders flask having a recess in its opposite sides, a plurality of chills extending across the flask, each chill having an end located in a recess and a retaining bar detachably secured in each recess, each retaining bar having a plurality of notches to receive the ends of the chills.
2. A molders flask having a depression in each of the opposite sides, a plurality of chills including fixed chills and a sliding chill, extending between the sides of the flask and having their respective ends located in said depressions and a retaining bar detachably fastened in each depression, said retaining bar having a plurality of notches to closely embrace the respective ends of the fixed chills and also having a notch to loosely embrace the respective ends of the sliding chill.
3. A molders flask having a cope portion and a drag portion each open at its respective top and bottom sides, a chill member fixed in each of said cope and drag portions of the flask having a surface flush with an open side of the flask and adapted to join each other at the parting line of the flask whereby each flask portion may be laid upon a pattern plate with the chill downward upon the pattern plate and an open side of the flask upwiard to be filled around the chill with san 4. A molders flask having a cope portion and a drag portion, each open at the respective upper and lower sides, a chill formed of two members divided at the parting line of the flask and one of said members being fixed in each of said cope and drag portions of the flask with its divided edge located at and flush with the parting edge of the respective flask member at an open side thereof.
5. A molders flask having a cope portion and a drag portion, a chill formed of two members divided at the parting line of the flask and one of each of said members being located in each of said cope and drag portions of the flask and means for mounting each chill member in its respective flask portion so that it will move relative to the flask in a direction with the greatest contraction of the casting to be molded.
6. A molders flask having a cope portion and a drag portion, a plurality of chills located within the flask and each divided on the parting line of .the flask, each opposite member of each chill being located in a respective cope and drag portion of the mold, means for immovably fixing some of said chill members in the respective flask portions and means for slidably mounting other of said chill members in the respective flask portions whereby they may move in a direction with the greatest contraction of the casting to be molded.
In testmony whereof I afiix my signature.
DONALD J. CAMPBELL.