US2284670A - Bearing and process of forming the same - Google Patents

Description

June 2, 194 w. E. M CULLOUGH ETAL 2,284,670

BEARING AND PROCESS OF FQRMING THE SAME Filed Feb. 2, 1940 FIG.7.

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INVENTORS WILLIAM E.McGULLOUGH BY EDWIN O.GOERKE W AfRNEYg Patented June 2, 1942 BEARING AND PROCESS OF FORMING THE SAME William E. McCullough, Detroit, and Edwin 0. Goerke, Dearborn, Mich., assignors to Bohn Aluminum & Brass Corporation, Detroit, Mich., a corporation of Michigan Application February 2, 1940, Serial No. 317,028

11 Claims.

The invention relates to bearings formed of alloys, chiefly of aluminum to which one or more other metals, such for instance as tin, are added to improve the bearing qualities. Heretofore, bearings have been formed of an alloy of aluminum containing from to of tin. Such bearings have been first cast and then machined to size. The machining operation is expensive, while the large amount of material removed further increases the cost of manufacture.

It is the primary object of the instant invention to reduce the cost of manufacture of bearings from such alloys, and further to obtain a product which has improved characteristics. To this end, the invention consists in the process and product as hereinafter set forth.

In the drawing:

Figure 1 is a diagrammatic representation of our improved extrusion process;

Figure 2 illustrates the manner of skiving or finishing the surfaces of the extruded member;

Figures 3 to 8 illustrate various cross sectional shapes of the extruded member.

Our improved process consists essentially in a novel method of extruding the metal particularly adapted to aluminum alloys containing from 5% to 15% of tin. The member thus extruded is of a cross sectional thickness substantially that of the fin shed bearing, so that it is only necessary to remove the oxide film from the surfaces thereof. The extruded member is then subjected to further operations for forming the completed bearing.

Extrusion method Pure aluminum and certain of its alloys can be fashioned into various cross sectional shapes by extrusion processes heretofore used. We have found, however, that an aluminum alloy containing from 5% to 15% of tin cannot be successfully extruded in such manner. This is primarily for the reason that there is a pronounced tendency for the tin component to sweat or be forced out of the alloy. Thus, if a billet of the alloy is heated to the usual temperature for extrusion, such as 800 F., and is placed in a container only slightly less in temperature in accordance with the general practice, the extruded product will not be satisfactory. We have, however, discovered that if the temperature of the billet and that of the container is considerably reduced, the extruded bar, preferably cooled by water. will hav desirable characteristics. As a specific example, we have found that a billet of the composition: aluminum, 89%; copper, 2%; magnesium, 1%, and

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tin, 8%, if heated to a temperature from 250 F, to 350 F. and placed in a container heated from 550 F. to 600 F. can be extruded without the sweating out of the tin constituent, and will .produce a bar having highly desirab e characteristics.

It will be appreciated that since the melting point of tin is 450 F., the unique feature of our invention lies in keeping the billet temperature below this point, and keeping the container and die temperature slightly above the same. Thus, the pressure to which the billet is subjected will not cause the expulsion of the tin content therefrom as would be the case if the temperature of the billet were above the melting point of tin. On the other hand, the temperature of the con tainer and the die being above the melting point of tin, a lubricating film of molten tin will be formed on the surface of the alloy which will reduce friction and facilitate extrusion.

As diagrammatically illustrated in Figure 1 of the drawing, A is the container which is maintained by suitable means (not shown) at a temperature from 550 F. to 600 F. B is the billet of alloy within the container, C is the compression plunger and D the die through which the metal is extruded. It is usual with apparatus heretofore used for the extrusion of aluminum to form the die at its entrance end with right angle or shearing edges. We have found, however, that with such construction when used with aluminum alloys having from 5% to 15% of tin, there is a tendency to tear and crack the edges and surfaces of the metal, but such difliculty we have avoided by forming the die with a curved surface at the entrance end, as indicated at E, Figure 1.

The extruded member may be varied in cross sectional contour according to the particular bearing which is to be formed or the subsequent steps employed in the completion of the bearing. Thus, in Figures 3, 4 and 5 the extruded member is in the form of a flat bar but with its edge portions of different shape. Figure 6 shows a bar having angle flanges or rib at the opposite ends thereof. Figure 7 shows a member of semi-cylindrical or segmental cross section, and Figure 8 shows a full cylindrical cross section. The extruded member which may be from fifteen feet to thirty feet in length is next drawn through a skiving die F to further accurately size the section and to remove the oxide film from the interior and exterior bearing surfaces. In case of the full cylindrical cross section this operation may be performed by internal and external breaching. The extruded member is next passed through a progressive die (not shown) in which it is submitted to the following consecutive operations:

(1) Cutting to prop'er length for a given bearmg;

(2) Cold coined to perfect half-circular cross section and with a radius or a longitudinal curve at each end;

(3) Perforated with oil holes;

(4) Stamped with oil grooves, as desired.

If the extruded member is in the form of a flat bar this must be bent longitudinally into arcuate form. If the extruded member is of arouate or full cylindrical cross section, then it is merely severed into bearing lengths.

We have found that extruded bars as above described, are capable of withstanding such subsequent cold operations, whereas cast material of the same composition is not susceptible to this amount of cold working without checking or cracking. Such difference we attribute to characteristics imparted to the material by the extrusion process.

What we claim as our invention is:

1. In a process of forming bearings from aluminum alloys containing from 5% to 15% of tin, the steps of extruding a. billet formed of such material preheated to a temperature from 250 F. to 350 F. and from a container at a temperature from 550 F. to 600 F. to form a member of predetermined cross sectional contour of substantially finished dimensions and subjecting said member to further operations for fashioning the same to finished form.

2. In a process of forming bearings from aluminum alloys containing from 5% to 15% of tin,-

the steps of extruding a billet formed of such material preheated to a temperature from 250 F. to 350 F. and from a container at a temperature from 550 F. to 600 F. to form a member of predetermined cross sectional contour of substantially finished dimensions, passing said member through a skiving die to accurately size the section and remove oxide film from the bearing surfaces thereof, cutting to predetermined lengths, and cold coining to finished size and form.

3. In a process of forming bearings'from aluminum alloys containing from 5% to 15% of tin, the steps of extruding a billet formed of such material preheated to a temperature of from 250 F. to 350 F. and from a container at a temperature from 550 F. to 600 F. to form a bar of approximately the cross sectional contour and dimensions of the finished bearing, passing said bar through a skiving die to accurately size the section and remove oxide film from the bearing surfaces thereof, cutting to bearing lengths, and cold coining to finished size and form.

4. A segmental bearing formed of extruded aluminum alloy containing from 5% to 15% of tin.

5. A segmental bearing formed of extruded aluminum alloy containing: tin, 8% copper, 2% and magnesium, 1%

6. In a process of forming bearings from aluminum alloys containing from 5% to 15% of tin, the steps of preheating a billet of the said alloy to a temperature less than the melting point of the tin constituent, and extruding the billet at such temperature.

7. In a process of forming bearings from aluminum alloys containing from 5% to 15% of tin, the steps of heating the container and die of an extrusion apparatus to a temperature higher than the melting point of tin, preheating a billet formed of the said alloy to a temperature less than the melting point of the tin constituent, and extruding the billet from the container through the die at the said temperatures.

8. In a process of forming bearings from aluminum alloys containing from 5% to 15% of tin, the steps of heating the container and die of an extrusion apparatus to a temperature notless than 550 F., preheating a billet of the said alloy to a temperature of not over 350 F., and extruding the billet from the container through the die at the said temperatures.

9. In a process of forming bearings from aluminum alloys containing from 5% to 15% of tin, the steps of heating a container and die of an extrusion apparatus to, a temperature from 550 to 600 F., preheating a billet of the said alloy to a temperature from 250 F. to 350 F., and extruding the billet from the container through the die at the said temperatures.

10. A bearing formed of extruded aluminum alloy containing from 5% to 15% of tin.

11. A bearing formed of extruded aluminum alloy containing: tin, 8%; copper, 2%; and magnesium, 1%.

WILLIAM E. MCCULLOUGH. EDWIN O, GOERKE.

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