US2357106A - Bearing construction - Google Patents

Description

Aug. 29, 1944.

1.. D. GRENOT v 2,357,106

, BEARING CONSTRUCTION Filed March 29, 1943 Fig.1]1 I \nvcnj'or: Leo D. Grenof hia Ai-fomzgtion engines.

Patented Aug. 29, 1944 UNITED STATESIPATENTI OFFICE BEARING CONSTRUCTION Leo D. Grenot, Oakland, Calif., assig'nor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application March 29, 1943, Serial No. 481,054

The present invention relates to improved bear- 4 Claims.

ing construction, particularly to the construction of bearings suitable for use in supporting rotating or reciprocating elements under heavy loads at high speeds and in the presence of a lubricant.

As is well known, relatively soft metals or alloys have been used as bearing metals for many years. One purpose of such use is to provide, as a support for a mo'vingelement, a contacting surface which will adequatelysupport a relatively hard shaft or the like and which. will, at the same time, avoid scoring or seriously abrading the shaft as it rotates or reciprocates against the bearing surface.

The softer metal compositions which are most extensively used at present for this purpose'are generally classified as babbitts and are either tinbase or lead-base alloys. The tin-base b'abbitts are mainly composed of tin; but usually contain varying amounts of antimony, copper or other metals to increase their hardness. The lead-base babbitts consist mainly of lead and usually con-.

tain appreciable percentages of one or more of the metals antimony, tin and copper, which serve in this instance'also as hardeners.

The primary requirements for a satisfactorybearing material are resistance to flow under working pressures and temperatures, resistance to fatigue, resistance to corrosion, particularly acid corrosion caused by inherent or added components of lubricating oils, good imbedibility and low friction properties. To these may be added, of course, the obvious desirability of low cost and ease of manufacture. None of the more important and commonly used bearing metals, such as'are employed in internal combustion engines for example, fulfills all of these requirements.

The various babbitt compositions (both tin and lead base) possess relatively high resistance to corrosion, good imbedibility and low frictionalcoeflicients. They are, however, unsatisfactory from the standpoint of resistance to flow and fatigue under the high stresses induced by the present day high compression internal combus- On the other hand, the commonly utilized cannot be. produced, however, by the simple process of heating the three essential metals, copper, lead and tin, as a corrodible lead-bronze hear-- ing metal is obtained, rather than a corrosion, flow and fatigue resistant copper-babbitt bearing metal. Since the desired distribution of the tin in the lead rather than in the copper cannot be obtained in this manner, other compromise methods of obtaining the same results have been attempted in the past,such as the random distribution of bronze filings and fragments throughout a babbitt bearing metal, for example. Bearings of this type, although a definite improvement over either babbitt or copper-lead type bearings alone, are still considered unsatisfactory fro the standpoint of non-uniformity of the finish d product with resulting unpredictable performance and difficulty in manufacture It is an object of the present invention to provide a bearing structure having high resistance to corrosion, fatigue and flow, good imbedibility and a. low frictional coefficient. A further object of the invention is to provide a composite bearing metal structure retaining the essential desirable qualities of both babbitt and copper-lead type bearing metals. A still further object is to provide sucha bearing structure which is both simreference also being had to the accompanying drawing which forms a part of this specification and illustrates a preferred embodiment of the invention.

In the drawin Figure I is an enlarged plan view of one embodiment of a bearing constructed.

- v, according to the present invention; Figure II is harder bearing metals such as those composed of copper-lead, cadmium-nickel or cadmium-silver, are more satisfactory from the standpoint of resistance to flow and fatigue under high stresses, but show poor resistance to corrosion.

The ideal bearing, at least from the basic considerations of resistance to corrosion and durability under present day conditions of usage,

a sectional elevation taken along the lines of II-II of Figure I; Figure III is a sectional elevation taken along the lines of IIIIII of Figure II.

The bearing structure according to the present invention comprises a conventional (steel) bearing backing to which is secured a wire mesh screen formed of a relatively hard bearing metal and throughout the interstices of which is dispersed a relatively soft bearing metal. The wire mesh screen may be formed of any of the common fatigue and stress resistant bearing metals,

particularly and especially the metals copper, silver, gold and platinum and alloys'of the same with each other and with other metals such as bronze, as well as pen metal, german silver, chinese silver, rhotanium, gold solder, phosphor bronze, manganese bronze, manganin, bell metal, etc. Any metal or alloy may be utilized for this purpose which has the desired properties of strength and which is at the same time not sufficlently hard or abrasive to damage, under operating conditions, the moving element which the bearing is designed to support.

As the relatively soft bearing metal component of the present structure all of the common babbitt type metals, both tin and lead base, and similar bearing metals and other alloys which have a high resistance to corrosion, low coefllcient of friction and sufficiently high melting point, imbedibility properties and resistance to wear to be considered comparable to the various babbitt metals come into consideration.

Referring to the drawing, in'a preferred embodiment the bearing structure comprises a steel bearing backing l to which is tinned or bonded with hearing alloy to a copper mesh screen con- I sisting of warp strands 3 and woof strands l. A

lead-base babbitt 2 is disposed below, above and in the interstices of the copper mesh screen, as shown. In this particular construction, a. copper mesh screen was chosen having warp strands 3 slightly larger than the woof strands and the babbitt metal removed from the top surface of the bearing until a small portion of each warp strand 3 stands exposed, as shown particularly in Figure I.

.The particular babbitt utilized in this instance comprised the following metals in the noted weight per cent composition: lead, 74.02%; antimony, 15.03%; tin, 10.12%; arsenic, 0.55%; copper, 0.28%. A 60 mesh copper screen was used having warp strands .0076 inch in diameter and woof strands .0067 inch in diameter. The interstices of the screen were filled with liquid babbitt, azinc chloride flux being used to insure adherence of the babbitt to the copper. The babbitt filled screen was then pressed into a babbitt bearing maintained at a temperature above the melting point of the babbitt. The composite bearing structure was cooled under pressure to insure bonding between the copper screen and the bearing backing andto avoid the formation of air cells beneath the surface of the screen. After the babbitt had hardened, the upper surface of the bearing was finished until the uppermost portionsof the warp strands of the screen were exposed. r

In some instances it will be found advantageous to retain a thin layer of babbitt over the wire screen rather than finishing until portions of the screen are exposed, such practice being particularly indicated when it is known that the hearing is to be used with especially corrosive lubricants. A babbitt layer of the order. of 0.001 inch to 0.0005 inch will generally be found satisfactory for such purposes. i

Other procedures for preparing structure according to the present invention may of course be followed. For' example, the screen element may simply be held in position by the bearing metal. For most purposes, however, it is preferred to bond the screen to-thebearing backing, which may' be accomplished in a number of ways, as for example by brazing, silver soldering, welding or thelike.-Inmany instancesitwillbefound ing backing with the babbitt alone, as in the example above. In the event that a heavy bearing is required, several superimposed screens may be used or, alternatively, 'a screen formed of thicker strands. If desired, as noted in the example above, the babbitt or other relatively soft bearing metal may be forced into the screen mesh under pressure while in a liquidv state, this procedure being preferable, in fact, when more than one thickness of screen is utilized.

For those applications wherein the bearing is to support a rotating shaft, the particular construction shown in the drawing, i. e., wherein portions of the warp strands only are exposed, is generally preferred. However, in many applications and particularly those wherein the bearing is intended to support a shaft that both rotates and reciprocates, it will be found desirable to form the bearing structure with a screen element wherein the warp and woof strands are of the same size, the finished bearing then having portions of both the warp and woof strands exposed. For rotating shaft support wherein a bearing having only portions of the warp strands exposed is utilized, the bearing is preferably constructed so that the greatest dimension of ex-' posed warp strand lies in a plane parallel to the axis of rotation of the shaft.

Comparative corrosion tests were made using various bearings in the drawings, including a bearing such that that shown under thrust conditions and in the presence of a detergent type lubricating oil, specifically an oil prepared from an asphaltic stock by solvent extraction and clay treatment and which contained 1.33% by weight of calcium phenyl stearate. The tests were run for a period of 20 hours ata speed of 2400 R. P. M.

and. temperature of 107 C. with a p. s. i. thrust load on the bearing face. The results obsentative bearing constructed according to the present specification. is fully equivalent to or better than the conventional babbitt bearings in its corrosion resistance and greatly superior to the most-commonly utilized non-babbitt bearings. Further, the bearing of the present invention will be found, in application, to be greatly superior to babbit type bearings in load-carrying ability and general resistance to fatigue and stresses. A still further advantage lies in the fact that the screen element serves as a reinforcement and in the event that crackin or breaking of the bearing metal occurs, as often happens with babbitt type bearings under severe operating conditions, the strands of the screen will serve to hold the broken section in its normal position.

I claim as my invention:

1. In a composite bearing structure the combination comprising a bearing backing and a bearing element disposed thereon, said bearing element comprising a relatively soft corrosion resistant bearing metal including a mesh screen V quite satisfactory to'bond the formed of a relatively hard fatigue and pressure said bearing backing, the warp strands of said mesh screen' being larger in diameter than the woof strands thereof at least some-of said warp strands extending to the upper surface of said 2 bearing element to form a plurality of exposed surfaces flush with the surface of said first named bearing metal, the greatest linear dimension of. said exposed surfaces lying in the direction of relative movement of the supported element over the'bearing surface.

2. In a composite bearing structure the bination comprising a bearing backing and a bearing element disposed thereon, said bearing element comprising arelatively soft corrosion resistant bearing metal including a mesh screen formed of a relatively hard fatigue and pressure flow resistant bearing metal, the warp strands of said mesh screen beinglarger in diameter than the woof strands thereof, said warp strands ex- I 'tending to the upper surface of said bearing element to form a plurality of exposed surfaces flush with the surface of said first named bearing metal, the greatest linear dimension of said ,exposed surfaces lying in the direction of relabination comprising a bearing backing and a bearing element disposed thereon, said bearing comelement comprising a babbitt bearing metal in eluding a mesh screen disposed therewithln, said mesh screen being formed at least predominantly ofcopper, said mesh screen being fixedly attached to said bearing backing, the warp strands of said mesh screen being larger indiameter than the woofstrands thereof, at least some of said warp strandsextending to the upper surface of said bearing element to form a plurality of'exposed surfaces fiush withthe surface of said first named bearing metal, the greatest linear dimension of said exposed surfaces lying in the direction of relative movement of the supported element over the bearing surface. 4. In a composite bearing structure the .com-

-, bination comprising a bearing backing and,a

bearing element disposed thereon, said bearing element comprising a relatively soft corrosion resistant bearing metal including a mesh formed ofv a, relatively hard fatigue and pressure flow resistant bearing metal, the strands of said mesh screen running in one direction being larger in diameter than the strands running at an angle thereto, said larger strands extending to the upper surface of said bearing element to form a plurality of exposed surfaces flushwith the surface of said first named bearing metal, the greatest linear dimension of said exposed surfaces lying in the direction of relative movement of the supported element over the bearing surface.

LEO D. GRENOT.

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