US2127204A - Mold - Google Patents

Description

Aug. 16, 1938. D. J. CAMPBELL MOLD Filed May 20, 1955 5 Sheets-Sheet 1 m: M wm.R C l JWM 0 m 0 p Aug. 16, 1938. D. J. CAMPBELL MOLD Filed May 20, 1935 5 Sheets-Sheet 2 8 M M 0 AM- B a 7 m R g 1 3 I l A 7 w y m w x a I /W' V M m i 0T u v 6 p 7 w W m 7 1 5 Vfl'll H m V a HT 6 M N T! w M Vm m m mm J f u M 0 ,g Ww

Aug. 16, 1938. D. J. CAMPBELL MOLD Filed May 20, 1955 5 Sheets-Sheet 4 INVENTOR Bony J (bu/ ,951.1. w

A TTORNEY D. J. CAMPBELL Aug. 16, 1938.

MOLD

Filed May 20, 1935 5 Sheets-Sheet 5 INVENTOR A TTORNEY BY DONALD J (5944 6221. fimwgwl m Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE tawa County, Mich.,

assignor to Campbell,

Wyant & Cannon Foundry Company, Muskegon, Mich., a corporation of Michigan Application May 20, 1935, Serial N0. 22,286

Claims.

This invention relates to metal founding, and is more particularly concerned with a method of producing molds for the casting of metal articles and which may be used for a great variety of articles, but which is particularly useful in connection with the casting of crank shafts for internal combustion engines. Other elongated articles, such as cam shafts for internal combustion engines, or other elongated shafts of irregular shape may be readily produced by use of the method for producing the molds therefor which I have devised, and which may be fully understood from the following description, taken in connection with the accompanying drawings, in which,

Fig. 1 is a plan view of a flask with the pattern plate and a reinforcing mold grid or arbor assembled ready for the reception of the molding sand.

Fig. 2 is a transverse vertical section through the flask, the pattern plate and arbor, and with the bottom plate applied and detachably connected thereto, as is done after the flask has been filled with sand.

Fig. 3 is a similar section of the bottom plate.

Figs. 4 and 5 are like sections of the reinforcing flask arbor and of the flask, respectively.

Fig. 6 is a similar section of the pattern plate shown located within and surrounded by the subplaten of a molding machine.

Fig. 7 is a side elevation of the reinforcing arbor.

Fig. 8 is a plan View thereof.

Fig. 9 is a plan of a mold section after the same has been produced.

Fig. 10 is an elevation of a crank shaft, two of which are produced in the mold shown.

Fig. 11 is a horizontal section through a complete mold for a crank shaft, the same consisting of two mold sections placed together and secured in fixed relation to each other.

Fig. 12 is an elevation of the complete mold shown in Fig. 11 associated with which at the upper end thereof, and being shown in section, are the gate member and pouring basin which are superimposed above the upper end of the completed mold.

Fig. 13 is a plan view of the pouring basin.

Fig. 14 is a central section therethrough, and

Fig. 15 is an underplan view of the gate member.

Like reference characters refer to like parts in the different figures of the drawings.

As illustrated in the drawings, the flask I has substantially parallel sides and parallel ends, being slightly tapered outwardly from its bottom to its top as shown. At the upper side are shoulders or flanges with wear resisting strips 2. At

the inner side and at spacedapart points adjacent the sides, pins 3 extend the full height of the flask, being provided with shoulders or collars 4 thereon between their ends which bear upon integral shoulders 5 cast with and extending in- 5 wardly from the sides of the flask.

A pattern plate 6 is designed to be located at the lower side of the flask. The plate is reinforced and supported by ribs 1 at its lower side, terminating at their lower ends in horizontal flanges 8 10 forming supporting pads which in practice rest upon the platen of a molding machine. At the upper side of the pattern plate 6 the patterns 9, in this case two identical patterns, are located and permanently secured. 16

A reinforcing arbor for the mold is adapted to be located within the flask. It is in the form substantially of a rectangular open grid having parallel sides and intermediate parallel bars II], with parallel ends and cross bars H (see Fig. 8) .20 thus forming an open grid which may be inserted downwardly into the flask as shown in Fig. 2. The undersides of the intermediate portions of the grid bars l0 and H may be cut away as at l2 so as to afford proper space for the reception 25 of the pattern. Pins l3 extend downwardly from the grid at its corners also midway between its sides and lugs l4, cast integral with the outer sides H) of the grid, extend outwardly and are divided so as to permit the passage of the pins 3, the lugs resting upon the collars 4. The arbor at its corners and ends has outwardly extending wings I5 as shown to afford further reinforcement to the mold which is made within the flask, the grid being located in the flask and retained in the mold after the flask is removed.

A bottom or strike plate I6 is likewise used, it being of a size to cover the upper end of the flask (Fig. 1) and having reinforced and strengthening ribs ll cast integral therewith, and also having outwardly projecting clamp lugs I8 at its side edges to cooperate with similar lugs I 8 on the flask over which a detachable clamp l9 may be placed to secure the plate and flask together. The bottom plate has many openings or perforations therethrough as shown.

In making a mold section the pattern plate is placed on the platen of a molding machine with the supporting pads or feet 8 resting thereon, and with the plate surrounding by the subplaten of the molding machine, upon which subplaten the flask is placed. The sub-platen of the machine is shown in Figs. 2 and 6 and indicated at Go. It is a permanent part of a molding machine. After the flask has been located in place on the sub-platen and with the pattern plate located within the sub-platen and resting upon the platen of the molding machine, the open grid or arbor is put within the flask as shown in Fig. 2. The flask is filled with sand, which covers the patterns 9 and completely surrounds all parts of the reinforcing grid or arbor. The molding sand is rammed or jolted to the desired density and any that projects above the plane of the upper edges of the flask is struck off, whereupon the bottom plate It is placed on the flask over the mold and clamped to the flask.

There are two ways in which the mold may be removed from the flask. One is to remove the whole assembly, consisting of the bottom plate, flask pattern, plate and reinforcing arbor, from the machine, turn the same over so that the bottom plate serves as a support and then draw the patterns from the mold, after which, by unclamping the clamps at I9, the flask may be withdrawn from the mold leaving the same with the reinforcing arbor therein and resting on the bottom plate. Another and a preferred method is to draw the patterns downwardly by lowering the platen of the molding machine after which the flask, the mold therein and the bottom plate are turned over, the clamps l9 removed, and the flask drawn upwardly away from the mold.

The mold is made of core sand with a suitable binder therein. After the pattern and flask have been removed therefrom it is baked in a baking oven thus providing a mold which, in characteristics, is similar to baked sand cores which are used in molding.

In the'manufacture of shafts, such as crank or cam shafts, a part of the mold cavities are made in one mold section such as section 20 (Fig. 9) and another part of the mold cavities in a similar mold section. The mold cavities 2i are provided by the parts of the pattern on the pattern plate 6 when joined together with the two baked sand mold sections located side by side, as in Fig. 11 provide a complete mold cavity for the shaft. In practice, in order to obviate the effects of shrinkage, as draws and pits which would occur from shrinking particularly in elongated articles, there may be provided parts 9a and 91) on the pattern to make feeder cavities in the mold, the first being shown in Fig. 1 to feed additional metal to heavy parts of a crank shaft where shrinking is liable to occur, and the latter at one end of mold to supply additional molten metal to feed into the upper end of the molten iron which is poured into the mold when the two mold sections are placed together and located vertically, as the same are located for pouring. The mold cavities 2| and the feeder cavities Zia and H2) (Fig. 9) are connected together so as to completely fill with molten iron upon pouring.

The section 20 of the mold made (Fig. 9) when the same has had the flask withdrawn therefrom, has openings 22 transversely therethrough made by the pins 3, collars 4 thereon and the shoulders 5. It is also contemplated that there shall be recesses and projections on the pattern plate so that the mold sections 20 made there are provided with corresponding projections 24 and recesses 23, such that when the two mold sections are placed together the projections 23 on the face of one mold section enter the recesses 24 on the other, thereby properly locating passed therethrough. These bolts are provided with heads 26 at one end between which and the adjacent outer side of a mold section washers 21 or thin metal plates or bands are located. The threaded ends of the bolts receive thumb nuts 28 between the inner sides of which and the adjacent outer side of the mold sections 29, similar washers, plates or bands 2'! are placed. The bolts pass through the spaces made in the lugs [4 as shown in Fig. 2.

When the two baked sand mold sections have been thus secured together they are placed in a vertical position on a suitable supporting base as shown in Fig. 12. Over the upper end of the complete mold a gate member 29, of baked core sand, is placed. The gate member has an opening 30 therethrough and on the underside thereof from said opening are gates 3! which branch and curve away from each other and are connected by cross gates 32 with openings33 made vertically through the gate member, one of which comes directly above each upper feeder cavity 2lb at the upper end of each of the crank shaft mold cavities.

Over the gate section 29 a pouring basin 34, also made of core sand, baked in the usual manner, is located. The'pouring basin has a well 35 into which the metal is poured and from which it flows into a shallower portion 36 and over a skim gate 31 which is disposed'directly above the opening 39 in the gate member, whereby the molten metal, after passing through the skim gate, follows the gates 3| to the openings 32 and thence into the mold cavities. There is also formed in the-pouring basin, directly above each of-the openings 33, a vertical opening 38, the upper end of which is closed by a baked core sand plug 39.

When the molten metal is poured into the well 35 and passes therefrom through the gates to the mold cavities, the air which is displaced by the metal rises into the spaces 38 and slowly passes through the bodies of the mold sections and of the pouring basin, thereby controlling the rate at which the molten iron may pass through the skim gate 31 to the mold cavities. Without the plugs 39 this rate of filling the mold cavities would be too fast, but the air trapped in the enclosed spaces 38 and passing therefrom with relative slowness through the body of the pouring basin operates as a check and furnishes a proper control to the rate of flow of the molten metal into the mold cavities. It is, of course, to be understood that the molds, like all other molds, are suitably vented so that air and gases can escape therefrom but not at the rate which they would escape if the upper ends of the openings at 38 were open.

The crank shaft 4|] (Fig. produced will have thereon parts, indicated in dotted lines at 49a and 40b, which are cut away to provide the finished casting. These parts, which are cut away, will furnish, when in a molten state, additional molten metal to the shaft to compensate for shrinkage and to eliminate draws and pits. Any draws, pitting or other imperfections will be in the parts 40a and 40b which are cut away. As the molten metal reaches the bottoms of the mold cavities first, and as the cavities are filled, this metal at the lower end will begin to solidify first and will have its shrinkage taken care of by the molten metal above the solidified portions until the upper end of the mold cavities are reached, whereupon the upper ends of the shaft portions will be fed from molten metal contained within the cavities 9b.

With this method of producing molds the use of a large number of flasks is not required, as one flask is all that is required in making a large number of molds; and duplication of flasks and patterns will be merely for multiplying production. In fact the only elements which must be duplicated in large numbers are the reinforcing open grills of arbors shown in Figs. 7 and 8. The mold sections will be of a relatively hard consistency so that the passage of the molten metal in the mold cavities will not act to break loose parts of the mold. The reinforcing arbor in each mold section helps to hold the sand against blowouts from pressure which might otherwise occur. In practical use of this method of producing molds exceptionally satisfactory and consistent results have been obtained. Large and economical production is attained, and the shafts or other articles cast are of a homogeneous character free from weaknesses due to pitting, shrinking, blowouts and the like.

The invention is defined in the appended claims, and is to be limited in no respect other than is required by the terms of said claims.

I claim:

1. In the art of molding, a flask open at its upper and lower sides provided with inwardly extending shoulder portions at its lower part and at opposed sides thereof, pins mounted in said shoulder portions and extending upwardly above the same to substantially the plane of the upper edge of the flask, and an open grille-like arbor having sides and ends and cross members, said arbor at opposite sides having outwardly projecting lugs divided between their sides for the passage of the pins therethrough, said arbor being located in the flask with the lugs engaged with said pins.

2. In the art of molding, a pattern plate with a pattern at the upper side thereof adapted to rest upon the platen of a molding machine with said pattern plate located within the sub-platen of a molding machine and with its upper sides in substantially the same plane as the upper side of the sub-platen, a flask open at its upper and lower sides resting on said sub-platen, said flask at the inner sides thereof being provided with vertically extending pins, and an open grille-like arbor carried and guided by and extending between the pins and having its upper edges below the upper edges of the flask, whereby sand may be placed in the flask to fill the same and cover the pattern and flll the open spaces in and cover said arbor, as specified.

3. In the art of molding, the combination of an open grid-like arbor having sides and ends and cross members, said sides having lugs extending outwardly, integrally formed pins extending from the corners of the arbor and reinforcing means extending alongside of each of the corners to reinforce the same.

4. A grid-like arbor as set forth in claim 3 in which additional pins are provided on opposite sides thereof between the corners and also additional reinforcing members are provided alongside of said pins.

5. In the art of molding, a flask open at its upper and lower sides provided with inwardly extending shoulder portions at its lower part and at both ends thereof, a reinforcing arbor, pins mounted on said shoulder portions and extending upwardly, above the same, said arbor at opposite sides having outwardly projecting lugs cut away to provide for the passage of the said pins therethrough, said arbor being located in the flask with the lugs engaged with said pins.

DONALD J. CAMPBELL.

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