US2365562A

US2365562A - Method of making porous metal bearings

Info

Publication number: US2365562A
Application number: US435453A
Authority: US
Inventors: Roland P Koehring
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1942-03-20
Filing date: 1942-03-20
Publication date: 1944-12-19
Anticipated expiration: 1961-12-19

Description

Dec. 19, 1944% R. P. KXOEHRING 2,365,

METHOD OF KING POROUS METAL BEARINGS 2 Sfieets-Sheet 1 Filed March 20 I l vwswr'an V Roland P [(aefimby 1115' HT rm vavs Dec. 19, 1944. R. P. KOEHRING I METHOD OF MAKING POROUS METAL BEARINGS .Filed uarcnzo, 1942 Y 2 Sfieets-Sheet 2 Hrrnmvss I Patented 1)...19, 1944 METHOD OF, MAKING POROUS METAL BEARINGS Roland P." Koehring, Dayton, Ohio, assignor to' General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 20, 1942, Serial No. 435,453

3 Claims. (01. 29-1495) This invention relates to a method of conditioning porous metal articles at the surface thereof and is particularly concerned with conditiony ing the surface of a porous metal article by means of mechanical 'applicatibn of another metal thereto.

An object of the invention is to provide a method and apparatus for mechanically forcing particles of metal into the surface pores of the porous metal article during sizing thereof whereby the surface so conditioned approximates the characteristics of the metals which are forced into the pores of the porous metal article.

A further object of the invention is toprovide a method whereby soft metal powders, such as lead, tin, antimony or alloys thereof, in finely divided form are carried by means of the fluid vehicle, preferably of lubricating character, and wherein said mixture is flowed over the surface of the porous metal article during the sizing application whereby particles of the soft metal are forced into the pores of the porous metal.

A still further object of the invention is to provide method and apparatus for conditioning the surface of a orous metal article wherein a sizing punch is utilized which includes fluid ducts therein that emit soft metal powder carried by the fluid vehicle during the sizing operation whereby the soft metal inLthe fluid vehicle is placed directly in the path. of the sizing punch so that particles ofthe soft metal are immediately forced into the pores of the porous metal.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accom panying drawings wherein preferred embodimens of the present invention are clearly shown.

In the drawings:

Figs. 1 through 4 show one type of apparatus used in carrying out the present invention dur ing the steps of the operation on a spherical metal bearing; f

Fig. 5 is .an enlarged fragmentary, sectional view of the bearing showing the conditioned surface thereon;

Figs. 6 through 9 show another type of apparatus in various positions for accomplishing the same results wherein a sizing punch is used which acts-as a means for supplying the metal powder in the lubricant.

- Fig. 10 is an enlarged fragmentary,-sectional shown in Figsj6 through 9.

When making" porous metal articles it is desirable to utilize inexpensive metals and then condition the surface thereof with a more desirable metal for the purpose intended. An example of such type of manufacture is a spherical hearing, such as is used in electric motors view of the sizing punch used in the apparatus often and the like, wherein the bearing is preferably self aligning,

Spherical bearings therefore rather than form the bearing from bronze it is economical and desirable to utilize porous iron and the like. ventional formulae of iron and graphite, either alone or with a binding metal, are formed in the desired shape under pressure and are sintered under suitable conditions of time, temperature and atmosphere to form a porous iron-bearing.

' of such alloys being preferably babbitt.

the bronze bearings in certain bearing characteristics as used in many specific applications although they are stronger. I. have found that these bearing characteristics can be markedly improved so that the bearing is highly suitable for its intended use by effectively lining the bearing bore with a soft metal powder, for example, 1ead,'tln, antimony, zinc or alloys thereof, one If the lining operationis carried out by an impregnation step, the cost of the bearing is again increased so that it is incompatible with the substitution of material. I, therefore, propose to form an effective lining such as the babbitt, simultaneously with the sizing operation.

In the majority of porous metal articles, sizing is resorted to to compensate for the physicalchanges such as shrinkage which occurs during thereof wherein a sizing punch of the desired diameter is forced through the bore and due to the ductility of the porous metal causes the bore to become enlarged to the desired dimensions. This operation canbe accomplished very well on cupreous articles or ferrous articles.

I have found that if a Babbitt powder, or any other desirable soft metal powder in a quite finely divided state, for example, 250 mesh, .is suspended in a fluid vehicle, preferably oil although vehicles which are not lubricating in character can be used with varying degrees of success is supplied around the bearing during the sizing operation, that as the sizing punch passes through the bore of the bearing, particles of the soft metal are mechanically forced into the sur- J face of the bore whereby the bore of the sized bearing has similar bearing characteristics to the soft metal. This bearing surface is highly desirable since the high portions thereof still remain iron or other metal whichforms the porous metal bearing and provides a strong load supporting structure for the shaft which is to be journaled therein while, the interstices between these high points present a soft metal bearing surface and therefore provide an ideal bearing surface. Bearings of this type, while carrying are of appreciable size in I order to obtain the bearing surfaces required and For this purpose conhigh loads, do not wear appreciably and therefore are quite desirable.

One form of apparatus which has been used with success is shown in Figs. 1 through 4 wherein it illustrates a porous metal bearing which is placed in a fluid reservoir 22 in a die structure it. positioning pin it in a bath of the liquid vehicle to be used which also includes the soft metal as at id. A punch section 30, having a contour similar to the die section 24, is provided through which a sizing punch 32 is passed. After the bearing to is in position, as shown in Fig. l, the punch section ill descends and clamps the spherical bearing in place, as shown in Fig. 2, in which position the bore of the bearing is filled with the fluid vehicle with the soft metal powder in suspension. The sizing punch it next passes through the bore and presses the pin it downwardly whereby the soft metal lining is impressed upon the surface of the bore of the bearing. Punch section Jill is removed together with the sizin punch it and the bearing is then forced upwardly on the die portion as shown in Fig. t whereupon the hearing may be removed. It is desirable to form the positioning pin with a valve therein, designated at M which includes a spring at so that the fluid vehicle and metal powder may be replenished therethrough.

Another type of the apparatus is shown in Figs. 6 through 9 wherein a die section llll is providcd which has a movable center portion ll which includes a semi-spherical die cavity M therein which is suitable for receiving the bushing lll. Preferably the upper portion of the die cavity llll is filled with a liquid lubricant carrying finely divided soft metal powder. Punch section it also includes a semi-spherical cavity which is adapted to fit over the bearing and likewise carrying the sizing punch M which is slidable therein. its shown in Fig. 7 after the bearing is in place the punch section it is moved downwardl and then the sizing punch 52 is passed through the bearing, as shown in Fig. 8. Whereupon the section t8 and sizing punch 52 are removed and the movable portion 12 of the die is forced upwardly so that the bearing 20 may be removed. In this particular apparatus the sizing punch provides the means for supplying lubricant and the soft metal powder to the bearing bore.

Fig. 10 shows a sectional view of this punch wherein a central duct 58 is provided within the punch which communicates by means of a plurality of apertures 58 at various stages of the sizing rings on the punch. The fluid vehicle with the soft metal powder is forced through the duct 56 and outwardly through the apertures 58 so that it flows directly into the path of the moving sizing punch whereby the soft metal powder is rndintained in the desired position at all times. Valve mechanism is also provided in this form for removingexcess liquid from the die cavity as is required. In both embodiments the valve 34 may be balanced by adjustment of spring 35 to cause varying degreesof hydraulic pressure to be exerted on the fluid vehicle and metal powder suspended therein. In this manner, as the burrushing punch descends, pressure is applied which forces the fluid vehicle into the pores of the bearing and thereby effectively filters out a layer of soft metal powder on the surface of the bore,

The bearing is preferably set over a' aaoases which powder is further forced into the pores of the porous metal by the burnlshlng action of the punch.

From the foregoing it is apparent that I have provided a facile method for effectively changing the frictional characteristics of the rubbing surface of a porous metal article. It is likewise apparent that treatment on a flat article may be made in a like manner, the main feature in the invention being that the pressure is applied to force the soft metal particles carried in fluid vehicles into the pores of the metal article while sliding in a plane parallel to the surface treated. It is also possible that the surface of the article maybe treated with some other metal which does not necessarily improve the frictional characteristics if such a surface is desired and it is to be understood that all such expedients come within the scope of my invention.

While the embodiments of the present invention as herein disclosed, constitute preferred forms. it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a method of effectively lining the bore of a porous metal bearing with soft metal powder and simultaneously impregnating the bearing with oil and sizing the bore thereof, the steps comprising: providing a porous metal bearing having a bore therein of a diameter slightly less than a diameter ultimately desired, providing a sizing punch of the desired diameter and greater than the diameter of said bore, forcing soft metal powder and oil into the pores of the bearings and simultaneously sizing the bearing bore by forcing .said punch through said bore while simultaneously supplying soft metal powder suspended in oil to the bore ahead of said punch.

52. The method of improving the bearing characteristics of a porous metal bushing, comprising the steps of providing a porous metal bushing formed from slntered metal powders and having a bore therein of a diameter less than the diameter ultimately desired, providing a sizing punch having a diameter substantially the diameter ultimately desired in said bushing bore, immersing said bushing in oil having fine particles of soft metal suspended therein, forcing said punch through said bore and ultimately forcin said soft metal powder into the surface pores of said bushing bore.

3. The steps in a method of providing a soft metal lining at the bore of a porous bearing and simultaneously sizing the bore of said bearing to a diameter substantially that desired comprising: providing a. porous metal bearing having a bore therethrough of substantially less diameter than the diameter ultimately desired, providing a. sizing punch having substantially the diameter desired ing bore by movement of said punch through the bearing bore whereby an effective soft metal lining is provided at the bearing bore and the bore isslzed to the diameter ultimately desired.

ROLAND P. KOEHRING.