Method of making brake drums

R. J. BENYA ETAL 3,005,259

METHOD OF MAKING BRAKE DRUMS

Sheets-Sheet 1

Oct. 24, 1961

Filed Nov. 24, 1958

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Oct. 24, 1961 r. j. benya etal 3,005,259

METHOD OF MAKING BRAKE DRUMS

Filed Nov. 24, 1958 3 Sheets-Sheet 2

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Oct. 24, 1961 r. j. benya et al 3,005,259

METHOD OF MAKING BRAKE DRUMS

Filed Nov. 24, 1958 3 Sheets-Sheet 3

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United States Patent Office

3,005,259

Patented Oct. 24, 1961

3,005,259

METHOD OF MAKING BRAKE DRUMS Robert J. Benya, Grosse Pointe Woods, and Felix Cole, Center Line, Mich., assignors to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware

Filed Nov. 24,1958, Ser. No. 775,886

Claims. (CI. 29—505)

This invention relates to lined brake drums and in particular to a method of making the same in a single press operation by impact extrusion.

In making brake drums and in particular aluminum brake drums having cast iron liners, a production problem exists in attaching the liner to the aluminum drum body. Some prior methods cast the aluminum body around the liner, but, this method is rather tedious and may often result in a loose connection between the body and the liner due to different coefficients of expansion of the aluminum and the cast iron. Methods which mechanically attach the liner to the body are also tedious and expensive due to the number of operations necessary to make a sturdy attachment.

It is a major object therefore of this invention to provide a single step die forming method for forming and attaching an aluminum brake drum body to a cast iron liner.

In this method, a substantially disc shaped aluminum blank initially frictionally secured to a hub is placed along with the hub in the cavity of a lower die, and a cast iron liner is initially frictionally secured onto an upper die which fits into the lower die. The dies are then brought together to impact extrude the cold aluminum disc into the cavities formed by the dies and into intimate contact with the hub and the liner. The direction and force of the flowed or extruded aluminum is sufficient to form a compression contact joint between it and the hub and liner.

Another object is to provide a method for forming an aluminum brake drum body to a desired shape from a blank of cold aluminum by utilizing cooperating impact extrusion dies and to attach a cast iron liner to said aluminum body during said forming of the body.

Further objects and advantages will become apparent from the following description and drawings, in which: _; FIGURE 1 represents a cross sectional view of a brake drum body and attached liner formed in accordance with this invention;

FIGURE 2 represents a view taken along line 2—2 of FIGURE 1 in the direction of the arrows;

FIGURE 3 represents a view taken along line 3—3 of FIGURE 2 in the direction of the arrows;

FIGURE 4 represents a variation in the keying structure of FIGURE 1;

FIGURE 5 represents a view taken along line 5—5 of FIGURE 4 in the direction of the arrows;

FIGURE 6 represents another variation of the keying structure;

FIGURE 7 represents an initial stage of the method of making the brake drum;

FIGURE 8 represents a second stage of the method; and

FIGURE 9 represents the last stage of the method.

Referring to FIGURE 1, a brake drum 10 is shown comprising an aluminum brake drum housing or body 12 and a cast iron liner 14 secured thereto by cooperating preformed keying ribs 16 on the liner 14 and keying ribs 18 formed by the present process on the body 12. The liner is further secured to the body by a compression contact joint as hereinafter explained.

As shown in FIGURES 4, 5, and 6, variations in the type of keying structure may be employed such as, for example, the inter-fitting wedge keying structure 20 of

FIGURES 4 and 5 and the keying projection 22 of FIGURE 6 having slot 24 therein through which slot the aluminum is extruded, as explained below.

A hub 26 having preformed splines 28 thereon is also 5 secured to the body 12 by an impact extrusion joint with splines 30 formed by the present process on the body 12 inter-fitting with the splines 28 on the hub. The hub 26 is tapered and the body 12 has a formed over annular retaining shoulder 32 to further insure retention of the 10 hub within the body 12.

Referring to FIGURE 7, which shows the first step in the cold impact extrusion process, an aluminum disc 34 of substantially the correct metal volume for making the drum body 12 and having an aperture 36 therein fric15 tionally receives hub 26 in said aperture which hub is placed in a cavity 38 of a lower die member 40 and rests on shoulder 42 therein. A mandrel 44 is inserted into the bore 45 of hub 26 to provide a backup therefor and also to retain the hub 26 and the disc 34 in proper 20 position in the lower die cavity 38. An upper die 46 having an annular recess 48 in the outer periphery thereof frictionally supports the liner 14 and holds said liner in the proper position with respect to hub 26 and disc 34. An outer shell 52 slidably receiving upper die 46 com25 pletes a cavity 54 into which the disc 34 will eventually be extruded or formed. This cavity 54 is designed to have the proper size with respect to disc 34 to be completely filled thereby and to cause said disc to be formed into very intimate compression contact with the liner 14 30 and the hub 26.

Referring to FIGURE 8, it is seen that movement of the upper die member 46 toward the lower die member 40 causes the aluminum disc 34 to flow or extrude into cavity 54 and into the aforesaid intimate contact with 35 the liner 14 and the hub 26, and as shown in FIGURE 9 the extruded aluminum completely fills cavity 54 and is in complete compressive contact with the keying portions of both the liner 14 and the hub 26. It is also noted that in this single step impact extrusion process 40 the hub retention shoulder 32 is automatically formed.