US1954460A - Method of forming flanged castings - Google Patents

Description

April 1934- H. L. STEEB 1,954,460

METHOD OF FORMING FLANGED CASTINGS Filed Oct. 27, 1952 2 Sheets-Sheet l firrylqjieel? wwawm l,

A1 1934- H. L. STEEB 1,954,460

METHOD OF FORMING FLANGED CASTINGS Filed Oct. 27, 1932 2 Sheets-Sheet 2 fwerzzorr Patented Apr. 10, 1934 UNITED STATES PATENT OFFICE fourths to Ill.

Application October 27,

2 Claims.

The present invention relates generally to methods of and means for forming flanged or ribbed castings and other parts as, for example, flanged engine cylinders, flanged brake drums and the like, and has for its principal purpose the provision of a method of and means for forming such parts quickly, inexpensively, and with accuracy.

For the purpose of illustrating the present invention I have chosen to disclose the same as applied to the manufacture of flanged cast metal brake drums for automobile wheels and the like.

It has been recognized that a cast metal ,brake drum is superior to drums formed of pressed steel or other metal and that braking conditions are greatly improved and the life of the brake drum is increased where cast metal is used In forming brake drums of cast metal and the like it is generally desired to provide some form of circumferential flanges for the purpose of dissipating the heat generated when the brakes are applied. These flanges, of course, are disposed on the exterior surface or periphery of the brake drum and present a problem of some difliculty in casting such a brake drum.

In forming flanged or ribbed parts and objects by casting according to methods formerly employed, the first step was the production of a matrix to receive the molten metal. This was accomplished by first forming a pattern or the equivalent and then bedding the pattern in a mold filled with molders sand and formed in two separable parts, the lower part of which is the drag and the upper part of which is the cope. After the sand was rammed or peened so that the impression of the pattern was retained, the parts of the mold box were separated and the pattern carefully removed in such a manner that the impression in the sand was not disturbed. The next step was to insert the required cores in the mold cavity, and then the proper openings and channels were formed in the sand by which the liquid metal may enter the mold cavity. Next the mold was closed and the metal poured so as to completely fill the mold cavity under sumcient pressure to secure a smooth sound casting. In this way, the exterior form or surface of the part was formed by the outlines of the pattern in the matrix while any holes, cavities, or pockets were formed by the core shapes, the cores being baked in an oven or the equivalent before being placed in the mold cavity.

As is well understood, the drawing or removal of the pattern from the mold before pouring the (llarence H. Dooley, Rock Island,

1932, Serial No. 639,787

portant operation. The patterns had to be properly parted so that each section thereof could be removed from the sand without-disturbing the impression therein. In certain instances, as in the casting of exteriorly flanged parts, it was practically impossible to remove the patterns without destroying the mold impression except by providing special 'sectionalized patterns with removable portions. Such patterns and the attendant operations were expensive. In practice, other expedients were also employed in casting articles having flanges or other overhanging parts; but in all of the prior methods a number of additional steps comparable to the steps mentioned above were required to cast articles having exterior flanges or projections thereon.

With the above factors in mind and in order to avoid the disadvantages referred to above, the present invention contemplates an improved method of and means for forming flanged castings such as flanged or ribbed engine cylinders, brake drums and the like and, briefly, the present invention contemplates utilizing cores for forming, not'only the interior cavities and the like, but also. the exterior of the article. For example, for forming the flanges or ribs, as on flanged brake drums and the like, instead of producing the matrix in the sand by the use of patterns having the desired exterior shapes, the present invention contemplates the use of cores having grooves therein, especially preformed separate cores which are plain and which can be formed in a very simple form of core box having smooth unbroken walls, the desired grooves or the like, which the core is required to have to cast the flanges or ribs, being formed in the core by a separate operation, such as, for example, by milling or grinding in a suitable machine, after the plain core has been baked in an oven or the like. The initial formation of a plain cylindrical core and the grooving thereof by a suitable machine avoids any necessity for complicated core boxes, sectional cores, and the like.

Another object of the present invention, having to do with the utilization of preformed cores as matrices for the castings, is, the use of a separate core which may be accurately milled to exactly the profile desired in one continuous operation and in complete form by which the resulting casting will be accurately formed, thus eliminating all subsequent machining or cleaning operations on the finished casting. By the use of a separate preformed core as a matrix for the casting there will not be any fins or the like that must be removed from the casting by a separate operation which would materially increase the cost of production.

These and other objects of. the present invention will be apparent to those skilled in the art after a consideration of the following detailed description disclosing, by way of example only, the formation of flanged or ribbed brake drum castings.

In the accompanying drawings:

Figure 1 is a side elevation of a core miller for grinding grooves in the separable or preformed core or matrix used in carrying out the principles of the present invention;

Figure 2 is an end view of the machine illustrated in Figure 1 and showing certain parts in sections;

Figure 3 is a sectional View taken through a core box used in forming the separable core;

Figure 4 is a view of the core after the same has been baked;

Figure 5 is a section taken through a mold flask showing a pattern in place therein with core prints for producing an impression in the green sand to receive the preformed core;

Figure 6 is a section taken through the drag of the flask, illustrating the position of the separable or preformed core in the mold cavity; and

Figure 7 is a section through the flask with the cope and drag closed and with the preformed and central core properly disposed in the impressions made by the core prints of the pattern.

Referring now to the drawings, the reference numerals l0 and 11 in Figure 3 indicate the two parts of a core box for forming the separable core indicated by the reference numeral 12. The core is made in theusualmannerpas byfilling the cavity with core sand and then rammed or peened to properly compress the sand in the core box so that the core will retain its shape which, in this case, is a cylindrical ring having sufficient draft to permit the drawing of the core from the core box. After the core has been removed from the core box the same is baked to harden the core after which it is ready to be milled or dressed to bring the same to proper shape to form the flanges or ribs on the completed brake drum.

According to the present invention, the preformed baked sand core 12 is brought to proper shape by means of a sand core miller illustrated in Figures 1 and 2. This machine preferably comprises a main frame 15 including suitable corner posts 16 and longitudinal and transverse frame bars 17 and 18 connected together in any desired manner. The frame 15 has provision for receiving a vertically shiftable bed 20 and for guiding the same in its vertical movement. The bed 20 is provided with suitable trunnions 21 or the equivalent with which links 22 are connected at their upper ends. The lower ends of the links are pivotally connected with cranks 24 suitably fixed to transverse shafts 25 supported in suitable bearings secured, preferably, to the longitudinal members 1'7. A socket 28 is secured to one of the shafts 25 to receive an operating handle 29 by which the cranks 24 may be rocked to raise and lower the bed 20. The shafts 25 are connected to move together by any suitable link means 30 so that the operation of the handle 29 causes both shafts 25 to be rocked together. The links 22 and crank 24 form toggle means for raising and lowering the bed 20 and are so constructed and arranged that when swung through and slightly beyond their dead center position the bed 20 is effectively supported in its upper position. Suitable stop means 31 are provided for limiting the rock- 62 by which the base block 51 may be shifted radiing movement of the cranks 24 in one direction to hold the cranks and links in position to main tain the bed 20 in its upper or operative position.

The bed 20 supports a movable base in the form of a rotatable table 35 having upstanding peripherally disposed centering fingers 36 and secured to the upper end of a rotatable shaft 37 suitably journaled for rotation on the bed 20. The shaft has secured to it a worm gear 40, and meshing with the gear 40 is a single lead worm 41 mounted on a driving shaft 42 which is operatively connected to be driven by a motor 43 or any other suitable source of power preferably but not necessarily mounted on the bed 20.

Rising from one end of the main frame 15 is an arm or support having provision at its outer end for shiftably receiving a slidable base block 51 upon which is mounted a driving motor 52 with its vertically disposed shaft 53 extending downwardly and carrying at its lower end a cutting or dressing tool 55 in the form of a grooved emery wheel having cutting flanges 56 formed thereon. The arm 50 is so constructed and arranged to bring the tool 55 in a position above the rotatable drum or table 35 and somewhat adjacent the edge thereof, and to provide for sliding movement of the base block 51 the arm .50 is pro vided with suitable grooves 60 or the like and carries a hand wheel 61 and an associated screw ally with respect to the rotatable table 35.

in operation the machine illustrated in Figure 1 and 2 is utilized to bring the baked sand core 12 shown in Figure 4 to accurate profile by milling or grinding the interior surface thereof. First, the table 20 is lowered by swinging the handle 29 in a clockwise direction, as viewed in Figure 1, this operation swinging the cranks 24 away from the stop means 31. Then the core is mounted on the rotatable table 35 and properly centered thereon by means of the peripheral fingers 36. Next, the hand wheel 61 is actuated to shift the tool 55 outwardly of the arm or support 50 and radially inwardly of the rotatable table 35 to permit the core 12 and the bed 20 to be elevated to the position shown in Figure 1. The motors 43 and 52 are then placed in operation, the motor 43 slowly driving the rotatable table 35 at a rate of approximately 15 revolutions per minute. Then the hand wheel 61 is turned to feed the tool radially outwardly of the table 35 to cause the tool to cut the grooves 60 into the interior surface of the core 12, the motor 52 rotating the tool 55 at approximately 3600 revolutions per minute and the tool being slowly fed against its work by the 1 operator manipulating the hand wheel 61. The stated rates of 15 and 3600 revolutions per minute are, of course, only relative and may be varied within relatively wide limits according to the character of work involved.

After the preformed separable core 12 has been milled or dressed to proper profile the same is ready to be inserted in the mold for the casting operation. Referring now to Figures 5, 6, and 7, the reference numeral '70 indicates a more or less conventional mold flask comprising an upper cope '71 and a lower drag '72 which is conventional construction in foundry equipment. For forming cast metal brake drums and. the like the molder will be provided with a pattern 73 of suitable shape to cast the desired type of brake drum and provided with core prints '74 and 75. The periphery or circumferential portion of the pattern '73-will be of larger diameter than the brake drum so as to provide an impression to receive the preformed core 12, this peripheral portion 76 thereby serving as a core print for this purpose.

After the proper impression has been made in the sand the flask is separated by removing the cope from the drag in the usual manner and then the pattern 73 may be removed. The pattern 73 may be formed in one, two or more parts as desired. After the separation of-the flask and the removal of the pattern 73, the preformed core 12 is placed in the impression in the sand formed therefor by the core print portion 76, as indicated in Figure 6 and the central core 77 is disposed in the impressions left by the core prints 74 and '75. Then the cope 71 is mounted on the drag 72, the proper risers, runners and gates being formed in the sand in the cope to provide for pouring the mold.

After the casting has been completed and cooled it is removed from the mold in the usual manner and the cores broken away from the drum. The provision of the preformed separable'core 12 ensures that the flanged exterior surface of the cast metal brake drum will be accurately formed and of. exactly the desired profile and without any fins or other imperfections. While I have shown the preformed core or matrix 12 as formed as a complete cylindrical section it is obvious that it may be formed of a plurality of assembled rings if desired and, further, it will also be apparent that the cylindrical core section 12 may be formed in'halves or other fractional parts, the principal feature being that exactly the desired exterior profile of the cast metal part can be reproduced without the provision of multi-part patterns and flasks. By way of example, it may be mentioned that the core 12 may be formed of a plurality of ings varying alternately in width so as to form the desired grooves for casting the ribs or flanges on the brake drum. Where desirable, these rings may be rounded or given any desired shape depending upon the desired section for the ribs or flanges. It will also be apparent that the principles of the present invention outlined above are equally applicable to the casting of parts other than brake drums, as, for example, flanged engine cylinders for air cooled motors, compressors, and the like, and for many other machine parts.

Therefore, while I have described above the preferred form of the present invention, it will be apparent that my invention is not to be limited to the specific details set forth-above but that, in fact, widely different means may be employed in the practice of the broader aspects of my invention.

What I claim, therefore, and desire to secure by Letters Patent is:

1. The process of making a substantially cylindricalcasting with external circumferential cooling flanges, which comprises forming an annular core of core sand with a substantially cylindrical inner periphery, baking said core to make it selfsustaining, cutting simultaneously a plurality of circular concentric grooves in the inner peripheral .wall of said core by engagement with a rapidly rotating cutting tool, enclosing said core-in a green sand mould, and pouring molten metal in said mould to form a casting.

2. The process of making a thin walled substantially cylindrical brake drum casting with a plurality of external peripheral-cooling flanges, which comprises forming an annular core of core sand with a substantially cylindrical inner periphcry, baking said core to make it self-sustaining, cutting simultaneously a plurality of circular concentric ooves in the irmer peripheral wall of said core by engagement with a rapidly rotating cutting tool and slow relative rotation of the core with respect to the rotating tool about the circular axis of the core to define the external flange surfaces of the casting, forming a second cylindrical core of a diameter suitable to define the inner peripheral wall of the casting, enclosing said cores in gancentric relation in a green sand mould and pouring molten metal in said mould to form the casting.

HARRY L. STEEB..

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