US2044815A - Method of centrifugally casting liners in brake drum shells - Google Patents

Description

June 23, 1936. A GEIQT 2,044,815

METHOD OF CENTRIFUGALLY CASTING LINERS IN BRAKE DRUM SHELLS Filed Aug. 7, 1931 2 Sheets-Sheet l I I 973 km I 1 llllll "=1 25 21 ATTORNEKS INVENTOR M'IZIM flflazyenl v A244? 11. J Qw w June 23, 1936r w D, G NT 2,044,815

METHOD OF CENTRIFUGALLY CASTING LINERS IN BRAKE DRUM SHELLS Filed Aug. 7, 1931 v 2 Sheets-Sheet 2 llli r 5: 62

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INVENTOR Iii/(121cm fl Yarymfi,

MZ AHW Patented June 23, 1936 UNITED STATES METHOD OF CENTRIFUGALLY CASTING LINERSINBRAKEDRUMSHELLS William D. Sargent, Newtiork, N. 1., assignor,

by means to Dnrai'er (Inc.)

asslgnmen Dover, DeL, a corporation of Delaware- Application August I, 1981, Serial No. 555,192 1 mm. (01. 22-200) The present invention relates to brake drums and a method of forming the same and embodies, more specifically, an improved composite brake drum construction having a cast iron liner and a malleable metallic shell, as well as an improved method of forming a brake drum of this character. r

The advantages of cast iron as a braking surface are now recognizedand a detail discuss-on thereof is not required herein. Suffice it to so! that cast iron provides an excellent braking surface which is uniform in character and action and is far superior to steel. To provide the necessary strength in brake drums formed of cast iron, it has been necessary, however, to include such a quantity of metal in the spider or supporting structure for the drum that objectionable weight results.

Applicant has made exhaustive studies of brake 2 drum structures formed of cast iron and of malleable metal such as sheet steel, and has found that the most serviceable form of brake drum is that in which a cast iron braking surface is used with a sheet steel shell. The problem of sup- 25 porting the cast iron structure upon .the light malleable metallic shell is one which has been very diillcult .of solution. In accordance with one brake drum construction covered in an application Serial Number 541,602 filed June 2, 1931, so the malleable metallic shell is shrunk onto a preformed cast iron liner which has been cast by a centrifugal operation. The present invention relates to brake drums of similar construction but formed by casting the liner of iron directly into 35 the malleable metallic shell. I v

The manifold advantages accruing from such I construction will be readily apparent and an obiect of the present invention is, accordinlly. to provide a method of forming a composite brake 40 drum structure including a cast iron braking surface and a light malleable metallic supporting structure therefor.

A further object of the invention is to provide a method of forming a brake drum of the above 45 character wherein an iron liner is cast directly into its malleable metallic supporting shell, such method including the centrifugal casting of the iron.

A further object of the invention is to provide ,50 a method of casting an iron liner centrifugally in a brake drum shell in such fashion that the liner is effectively engaged by the shell to prevent displacement thereof.

A further object of the invention is to provide 55 a method of the above character wherein the diftherein under radial compression.

ference in coefiicient of expansion of cast iron and steel is utilized to provide a composite brake drum construction wherein an iron liner, cast into a malleable metallic shell, is maintained 5 The foregoing objects are attained specifically by a method including the preheating of sheet steel shells and centrifugally casting into the preheated shell, a auilicient quantity of iron to form a liner therefor. Upon pouring of the iron 10 into the rotating shell, the temperature ofthe iron and shell will reach a common value, from which value further cooling of the liner and shell causes the shell to compress the liner by reason of the greater coeflcient of expansion of the sheet 15 steel shell as compared to that of the cast iron liner.

a A further object of the invention is to provide a composite brake drum structure including a castiron liner effectively engaged by a sheet steel A obiect of the invention is to provide a composite brake drum construction including an iron liner cast centrifugally into a supporting shell, means being provided to prevent extrusion c of the metal of the liner.

A further obiectof the invention is to provide a brake construction of the above character wherein the iron liner is cast centrifugally directly in the shefl. 80

A further object of the invention is to provide an improved machine for centrifugally casting iron liners in malleable metallic shells.

Further objects of the invention, not specifically enumerated above, will be apparent in connection with the accompanyin description wherein reference is made to the accompanying drawings, in which:

Figure 1 is a view in vertical section, taken through a machine constructed in accordance with the present invention, and showing a shell which is ready for the casting operation.

Figure 2 is a detailed view in section showing a modified form of shell.

' Figure 3 is a detailed view in section, similar to Figure 2, showing the manner in which one form of brake drum shell is adapted for the casting operation to prevent extrusion of the metal of the liner.

Figure 4 is a view in section, similar to Figure 1 showing a modified machine for casting composite brake drums in accordance with the present invention.

Referring particularly to Figure 1, a foundation for a casting machine is shown at Ill and a formed with a recess II in which an electric motor l2 or other suitable power source is received. A rim 19 may be formed about the recess to provide a mounting for a standard l4 upon which a manually operated lever I9 is pivoted. Spring l9 normally urges the lever into the position shown in Figure 1 and a stop l1 limits such movement.

A power shaft ll of the motor l2 carries a sleeve 19 which is secured thereto by means of a set screw 29. Sleeve I9 is formed with a horizontal table 2| upon which bosses 22 are formed. Sleeve 29, ccaxially with the shaft l9, serves as a centering means for the shell and pouring plate, described hereinafter.

A pin or pins 29 are provided on the table 2| to afford an effective driving connection between the table and a brake drum shell 29. The shell 29 is preferably provided with a cylindrical flange 21 which is adapted to engage, snugly, the exterior surface of sleeve 23. Recesses 29 are also provided in the shell 29 to facilitate the securing of the shell to an appropriate wheel and these recesses are utilized as recesses within which the driving pins 29 engage.

If desirable, a convenient means may be provided for elevating the shell from the table 21 after the casting operation has been completed. To afford such means, a plurality of litter rods 29 are slidably mounted in the table 2|. Collars 99 on these rods limit the downward movement thereof and the upward extremities of the rods engage a cooperating surface of the shells 29. An annular carrier M is suitably connected to the lower extremity of the rods 29, the carrier serving as a track against which rollers 32 engage to elevate the rods 29 simultaneously. Rollers 32 are Journaled upon the extremities of arms 33 which form a forked extremity upon lever I5. Obviously, this lifting mechanism may be dispensed with without departing from the scope of the invention.

Within the sleeve 23, the hub 99 of a pouring plate 34 is received, the pouring plate being formed with an upper concave surface 39 upon which the metal is poured. Any suitable means may be provided to secure the pouring plate 34 effectively within the recesses formed by the sleeve 29.

While it is recognized that a number of ways of securing the pouring plate in such position may be utilized, the structure shown herein includes a solenoid or electromagnet 98 which may be conveniently energized when the pouring plate 94 is placed in position within the sleeve 29. Slip rings and brushes may be utilized to transmit current from a suitable source to the rotating magnet and, in as much as this specific structure forms no part of the present invention, a detailed description thereof will not be made herein.

To facilitate movement of the pouring plate the standard i4 is provided with spaced arms 99 in which a shaft 99 is journaled. Spaced collars 91 are pinned to the shaft and spring 99 engages the lower collar to urge the shaft 99 normally upwardly. A sleeve 99 is journaled on the shaft between the collars 91 and is formed with a pin or pins 19 engaged by the slotted extremity ll of a lever I2. The end of lever I2 is pivoted on the standard l4 at I3 and link 14 is pivoted on the lever 12 at 19. The lower end of arm 14 is pivoted at 19 to a lever H which is provided with a treadle 18 and is pivoted at 19 upon the standard l4. To depress the pouring plate and position the same preparatory to pouring, the treadie 19 is depressed and subsequent energization of the magnet 99 maintains the plate in pouring position.

It will be seen that the shell 29 is formed with a dust guard 39 and a lip 49 which extends in- 5 wardly from the adjacent liner supporting portion of the shell to prevent extrusion of the metal from the shell. A modified form of shell is shown in Figure 2, the liners within the shells shown in Figures 1 and 2 being indicated by a dot and dash line. It will thus be seen that the lip 49 effectively prevents extrusion of the metal of the liner from the shell. It may be preferable to form the shell with a circumferential channel or channels therein in order that the iron, when cast, may flow into such channels and increase the area of contact between the shell and iron. In the forms shown, these channels are curved in Figure l, tapering in depth in Figure 2, and curved with a width substantially less than the width of the shell in Figure 3. The specific form of channel, however, constitutes no part of the invention and it will be readily seen that channels of varying width and depth may be formed in the shell without departing from the scope of the 25 present invention.

In Figure 3 means is shown for facilitating the casting of iron liners within shells which are not formed with lips to prevent extrusion of the metal.

In this construction, a ring 4| is provided with a 30 cylindrical flange 42 whichis adapted to engage within the adjacent shell portion. Screws 42 enable the ring to be secured to the shell by engagement with the dust guard 99 thereof. The casting of the iron liner within the shell shown 35 in Figure 4 results in a liner having an interior surface indicated by the dot and dash line.

In the construction shown in Figure 4 the rim l3 receives a standard 44 in place of the bracket l4. The motor, rotating table, and shell elevating mechanism are similar to the corresponding elements described in connection with Figures 1 and 2. Instead of positioning the pouring plate by means beneath the table 2|, the plate is centered by a mechanism can'ied by the standard 44.

To this end, a pouring plate 49 is provided having a centering cone 49 upon its hub 41. The pouring plate is formed with an upper. concave pouring surface 49 and the stabilizing legs 49, as described in connection with Figures 1 and 2. A vertically slidable shaft 99 is mounted upon the pouring plate 49 and is journaled within bearings 9|, formed upon an extension 92 of the standard 44. Collars 93 are secured to the shaft 99 and spring 94 normallyurgesthe shaft 99 and pouring plate 49 into the position shown in Figure 5. A sleeve 99 is ioumaled upon the shaft 99, between the collars 99 and carries a pin or pins 99 which are engaged by the slotted extremity ll of a lever 58 which is pivoted at 99 upon an extension 99 so of the standard 44. The other. end of lever 99 is connected to a rod 9| which is pivoted intermediate the ends of a treadle lever 92 which is pivoted upon the standard 44 at 99.

It will thus be seen that spring 94 urges the es centering cone 49 into a-cooperating conical socket 94, formed in the table 2|, and the sleeve 21 on the drum 29 engages the hub 41 to be centered thereby. Initial movement of the lever 92 elevates the pouring plate from the shell 29 and then engages the extremity of lever l9. Continued movement of the lever 92 elevates the shell 29 and the latter is thus cleared from the table 21 and may be conveniently displaced therefrom.

The foregoing mechanism thus provides a convenient apparatus by which the centritugal casting operation is eflected, the pouring plate serve ing to distribute the metal effectively within the shell .26 and also to center the shell and clamp the elements in pouring position.

The thickness of the cast iron liner may be deierminedeither by forming a lip on the steel drum or by providing a suitable temporary lip or flange for the casting operation, such flange being removed upon completion thereof.

It has been found that the composite drum structure is more serviceable ii! the casting operation includes the 'preheatingoi the shell before the pouring of the iron thereinto. To this end,

the shell is heated preferably to a temperature between 500 and 1200, after which the iron is poured thereinto during rotation of the shell. Alter pouring, the iron 01 the liner and the metal of the shell reach substantially the same temperature, upon further cooling from which temperature the metal of the shell shrinks at least I as much as the iron 01 the liner to preserve an intimate contact therebetween. In reality, the iron of theliner is compressed by the metal of the shell and is thus eilectively secured therein. In this fashion, a thin steel shell, having the 5 desired strength, is formed with a braking surface of excellent character and wearing qualities and the structure is such that the two metals are permanently secured together.

While the invention has been described with 10 specific reference to the construction shown in the accompanying drawings, it is not to be limited, save as defined in the appended claim.

I claim as my invention The method or casting centriiugally comprising 15 preheating a comparatively thin shell to a temperature between 500 and 1200 degrees Fahrenheit, rotating the shell upon a vertical axis, and pouring metal thereinto.

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