US2158461A - Method of making bearings - Google Patents

Description

May 16, 1939. R. P. KOEHmNG ET AL v 2,158,461

METHOD OF MAKING BEARINGS Filed May 2s, 1935 Patented May 16, 1939 UNITED STATES 2,158,461 ivnrrnon or Mama BEARINGS Roland P. Koehring and John M. Hildabolt,

Dayton, Ohio, assignors to General Motors Corporation, Detroit, Mich., a corporation of Dell aware Application May 23, 1936, Serial No. 81,432

' bearings and the like.

An object of this invention is to provide an improved method of fixing a metal layer of sintered finely divided metal powder to a relatively high-melting metal backing such as a ferrous metal backing. A more specific object is to provide an improved method of xing a lining containing a large percentage'of lead to a steel back'- ing strip.

There is now an increasing interest in high leaded bronzes for bearing purposes and there have been numerous attempts `to produce. economically high-leaded bronze bearings.

One attempt along this line has been the development of a process wherein the molten leaded-bronze alloy is applied to a strip of steel in special equipment designed for the purpose.

Another attempt has been the sweating together of previously made strips of the leadedbronze alloy and tin-coated steel.

The method of this invention is fundamentally different from the above methods in that the bearing lining is formed from finely divided metal powders, of the desired composition and proportions, which are compacted directly upon the backing strip and thereafter sintered in situ thereupon, which integrates the bearing lining and simultaneously bonds the same very strongly to the backing strip.

Further objects and advantages of the present invention'will be apparent from the following description, reference being had to the accompanying drawing ,wherein a preferred embodi-l ment of the present invention is clearly shown.

In the drawing: Fig. 1 is a somewhat diagrammatic View showing both the step of compacting the metal powder upon the backing strip and the step of sintering the compacted layer in situ upon. said 1 backing strip.

Fig. 2 is a sectim taken on line 2*-2 of Fig. 1.

, Fig. 3 illustrates a nished rolled bushingwhich has been rolled up from a short` length of the composite metal stripmade b'y the process of this invention. 4

Similar'reference characters refer to similar parts throughout.

According to this invention a -loose layer III c embedded therein by the high pressure.

spaced above the strip II moving along at a' slow uniform speed to provide a smooth quite loose layer I of uniform thickness. The strip II is previously provided with a relatively thin plating 9 of relatively soft metal thereupon. This soft metal coating 9 may be terne plate, lead, tin, or other suitable soft metal alloy plating and is preferably applied by a single dipping of the backing strip II in the molten relatively lowmelting point soft metal or metal alloy. 'I'he thickness of plating 9 is preferably around .0002 inclhi, but in some cases may be as much as .001 inc When the strip I I with the loose metal powder layer I0 passes between the pressure rolls I2 and -I-3 the very high pressure compacts the metal powders to a high degree, causing these powders to cohere very firmly together and to adhere very firmly to the soft metal plating 9-on strip II. The thin plating 9 of strip II is soft and as a consequence the metal particles are partially The adherence of the compacted strip I0' (when made from 90 parts copper, 10 parts tin and 20 parts lead) to the plated strip II after passing between the pressure rolls isso strong that ithas been found that the layer 'I0' can hardly be chipped on with a knife, nor will it come off by bending a sectionof the composite strip over a threequarter inch radius with the layer I0' on the outside., In other words, the compacting pressure is sufcient to provide a composite strip which can be very roughly handled after leaving the pressure rolls and before sintering same.

Preferably the compacted strip, after leaving the `pressure rolls I2, I3. passes directly into a sinteringfurnace 20, as shown diagrammatically in Fig. 1, and is there heated to such a temperature and for such a period as willl cause the metalk particles of the compacted layer I0 to partially fuse or alloytogether and form a strong rigid somewhat porous structure and at the Sametime be strongly directly bonded to the steel strip II.

During such sintering the plating 9'of soft metal melts and is absorbed into and may be alloyed with the sintered structure, so that in the final product theplating 9 has disappeared as such and no longer forms an intervening stratum-beftween the steel strip I I and the sintered structure. .Hence ,the nal bondbetween the steell strip II and the sintered structure is a` direct alloy bond which vwill not melt loose at the relatively low melting point ofthe metal of plating 9. This sinteri'ng step should take place in a reducing atmosphere Within furnace 20. 'Such reducing atmosphere sintering furnaces are now well known and need not be illustrated and described in much detail herein. For a more complete disclosure of a reducing atmosphere suitable for the sintering step of the method of this invention reference is made to our copending ap- I plication S. N. 683, nled January '7, 1935. A su'itable reducing atmosphere for this method conslats of flue gas made by incompletely burning natural gas and having from 1% to '7% C0, 7%

'to 11% CO2, 1% to 7% hydrogen, and as little water vapor as is practically possible, for instance, about three-tenths of a pound of water vapor per 1,000 cubic feet of the flue gas. The water vapor in the flue-gas should be removed 'by refrigerating the iiue gas and thereby condensing the water and removing it therefrom.

. The dried flue gas is then passed into the sintermits these openings 23 and 24 .to remain. sum-v ciently open for the continuous passage therethru of the compacted strip being sintered. 25

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designates a series of electric heating elements which serve to maintain the sintering atmos-v phere in chamber 22 at the desired sintering temperature.

As a more specific illustration of the method of this invention thefollowing is given: A long steel strip having an ordinary commercial terne plate coating on both sides thereof may be'used as the metal backing strip II.

finely divided copper (90 parts), tin (10 parts) and lead (20 parts to 100 -parts depending on the desired lead content in the final bronze -layer). 'I'he compacting pressure obtained by the pressure rolls I2, I3 should be such. as will reduce the thickness of the loose layer i0 to a compacted layer I' having about one-third the thickness of `the loose layer. The pressure on rolls I2, I 3'may Vbe adjusted by means of the adjusting screws 30 to obtain the desired reduction in thickness, as will be obvious from the drawing. Spacer rings IB may be used on one of the rolls I2 or I3 to limit the thickness of the compacted layer I0 to the -exact thickness desired in any given case. Too great a pressure in compacting may result in blisters in the lining I0' after sintering. The formation of such blisters seems to be a functionv of the pressure used in compacting the metal Powder and the furnace temperature. Hence whenever blistering occurs the compacting pres-A sure should besomewhat reduced, or else the sintering temperature shouldbe lessend somewhat.- The correct pressure and temperatures can v be readily determined for any given case by simple trial. There seemsto be a limited thickness of metal powder which can be rolled on for each diameter of pressure rolls used. For instance,

when pressure rolls I 2, I 3 of 2inch diameter are used, a loose layer I0 of metal powder'having a thickness of .024 inch can be successfully rolled down to a thickness of .008 inch. When a greater `thickness of layer I0' is desired, larger diameter v pressure rolls should be used. With 8 inch diameter pressure vrolls a loose layer I0 having va thickness of .075 inch can be successfully rolled down toathickness of .025 inch. For a still The loose layer I0 of metal powders may be a homogeneous mixture of greater thickness of layer I0' still larger pressure rollsA I2, I3 should be used. The speed of rolling is also an important factor, as too fast a speed causes 4the metal powder to pile up ahead of the rolls I2, I3, or actually tends to blow the powder away. In the case of 8 inch diameter pressure rolls a speed of one revolution per minute is preferred, or a linear speed for the strip I I of about 2 feet per minute is very satisfactory.

'Ihe sintering temperature used in the sintering chamber 22 is preferably about 1 500" F. and the time periods for such sintering should be such that the copper and tin powders forming layer I0' lead solidifies in' its finely dispersed state and hence remains in the bronze structure in its nely dispersed uniformly distributed form. Also during such sintering the original terne plate coating 9 will melt and become absorbed by the porous bronze structure in a manner similar to that described above for Y the lead powder content. Terne plate ordinarily is composed of about 3 parts lead and one part tin. During sintering the terne plate coating '9 melts and disappears as such, its lead content being simply added to the other lead and its tin content being simply added to the other tin content in the metals being sintered. l

'I'he sintered strip emerging from outlet 24 of the chamber 22 should be cooled in a non-oxidiz ing atmosphere. Then it rxiay be kept in long straight lengths, or it may b e coiled up in large. coils, and transported to a machine for cutting and'forming bearings therefrom. Short lengths of this strip may be cut oil to the proper length' and coiled up'into a full circular form to form the split bushings 40 shown in Fig. 3, which have an outer relatively strong steel back 4I and an inner lead-bronze lining 42 which is strongly bonded to the steel. back by the above-described sintering operation. Or any other desired form of bearings maybe made from the-strip, for in stance, half-round bearings or bearing caps for v the crank shaft and connecting rods of automobile engines. In such cases the steel back may be made as heavy as desired and-provided with any desired kind of retaining means for properly holding the bearing rigidly xed in place.

The principles of this invention are obviously not limited .to making bearings, but may be used to advantage in forming many articles having one layer of metal having more or less precisely specied ingredients and proportions which layer is strongly and directly bonded to a second and distinct metal layer orbacking having other desired characteristics. Y

While the embodiment of the present invention as herein disclosed, c nstitutes a preferred form, it is to be unders Y that Votherforms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

'I0 l. 'Ihe steps in a continuous method of xing a liningto 'a ferrous metal back, comprising: pro- Y viding a thin highlead-content prime coating upon a ferrous metal strip, distributing a unifornr' f surface of said strip, compacting the loose layerl upon said relatively soft coated surface by-high surface of said strip and compacting it in place thereupon with a high pressure and thereby causing said layer of bearing metal to adhere firmly to said strip, then removingjsaid high pressure upon said compacted lining and subsequently" sintering said compacted bearing metal layer in situ upon said strip in a reducing atmosphere and thereby greatly increasing its strength and directly bonding it to said strip.

2. 'I'he steps in a continuous method of fixing a lining to a ferrous metal back, comprising: providing a thin prime coating of relatively soft metal upon a ferrous metal strip, applying a uniform layer of loose powdered bearing metal upon the coated surface of said strip and compacting it thereupon by passing said strips with the looseA powder thereon between pressure rolls, then subsequently sintering said compacted layer in situ upon said strip in a reducing atmosphere at a temperature and for a time period suilicient to tributing a uniform layer of powdered metal upon cause the compacted metal particles of the bearing metal layer to partially fuse or alloy together and with the relatively soft metal upon said strip.

3. The steps in the method of progressively providing a lining of a lower-melting metal upon an elongated backing of higher-melting metal, comprising: coating a surface of said backing with.

a thin coating of relatively soft metal, progressively distributing a loose layer of the lining metal in nely divided formupon the coated surface of said backing, progressively compacting the loosev layer of lining metal upon the backing by high pressure and thereby causing said layer to adhere firmly to the soft metal coating upon said backing, then removing said highpressure upon said compacted lining and subsequently sintering said compacted lining in situ upon said backing in a reducing atmosphere and thereby increasing its strength and directly bonding it to said backing,

4. The steps in the method of progressively providing a lining of a lower-melting metal upon an elongated backing of higher-melting metal, comprising: coating a surface of said backing with a thin coating of relatively low-melting metal, progressively distributing a loos layer of'the lining metal in finely divided form upon the coated surface of said backing, progressively compacting the `looserlayer of lining metal upon the backingby passing said backing with the lining layer thereon between pressure rolls, then subsequently sintering said compacted layer in situ upon said backing in a reducing atmosphere and thereby substantially integrating the structure.

5. The steps in a continuous method of providing a leaded-bronze lining on a ferrous metal back, comprising: providing a relatively soft high lead-content coating upon a ferrous, metal strip,

applying a loose layer of metal powder including finely divided lead and copper upon the coated pressure and thereby causing said layer to adhere firmly to said strip. then removing said high -pressure upon said compacted lining and subsequently sintering said'compacted layer in situ upon said strip in'a reducing atmosphere and thereby substantially integrating the structure.

6. The steps in a continuous method of providing abronze lining containing a high percentage of leadto a ferrous metal back, comprising:

the coated surface of said strip and progressively passing said strip together with said loose layer of metal powder thereon endwise between pressure rolls and thereby compacting said layer and causing it to adhere to the soft metal coating upon said strip; then subsequently passing the composite strip thrula sintering chamber in a reducing atmosphere and thereby substantially integrating themetal structure thereof, then cutting said strip to short lengths and individually bending the blanks thus formed into curved shape to form bearings.

8. The steps in a method for continuously applying a porous metal lining comprising at least two different metallic constituents upon a ferrous strip, which strip may subsequently be cut into short lengths to be used in' the formation of 1;`

bearings, comprising: providing a long length of ferrous strip materialcoating a surface of said strip with a thin coating of soft metal, progressively distributing a uniform layer of powdered metal upon thecoated surface of said strip,

compacting the layer of powdered metal in place upon the strip and thereby partially embedding strip by pressure and thereby causing said layer the powdered metals into the soft metal coating upon the strip to cause the layer to rmly adhere to the strip, and then subsequently sintering the compacted powdered metal layer in situ upon the strip. in a reducing atmosphere and at a temperature above the melting point of the lowest melting constituentmetal and below the melting point ofthe highest melting constituent metal in the powdered metal layer and thereby form a strong and rigid alloy'layer which is bonded to the said strip by an alloy bond.

9; The steps in a method for continuously applying, a porous bronze lining having lead dispersed withinl the pores thereof upon a metal strip of highermelting point than that of anyv providing a thin high lead-content coating upon ai ferrous metal strip, applying a loose layer of finelydivided-bronze-forming metal powder and nely divided lead upon the coated surface of said strip, compacting the loose layer upon said ofthe metal powders in the bronze lining comprising: providing a long length of strip material,-coating one side of the strip material with a thin coating of metal of high lead content', progressively applying a uniform layer of powdered' bronze-formingpowders to the coatedsurface of said strip, compacting the bronze-forming powders on the -surface of the strip by passing the strip with the bronze-forming powders thereon between pressure` rolls, subsequently sintering said compacted layer in situ upon said strip in.

a reducing atmosphere, and at a temperature intermediate the melting points of the constituent metal powders contained in the powdered metallayer for a time suicie'nt to caus'e the powdered metals to alloy and thereby form a strong rigid bronze structure and simultaneously cause the metal powders to absorb the high lead content coating, said bronze layer being thereby directly bonded by an alloy bond to the metal strip.

. 10. 'Ihe steps in a method for continuously applying an alloy metal lining comprising at least two component metals upon a metal strip which the lining comprising: supplying a long length of strip material, coating the surface of said strip material with a relatively soft metal, progressively applying a uniform layer of powdered metals on the coated surface of said strip, compacting the metal powders on the surface of the strip by passing the strip with the metal powders thereon between pressure rolls, subsequently sintering said compacted metal powders in situ upon said strip in a reducing atmosphere and at a temperature above the meltingpoint of th lower melting point metal powder in the powder layer and below the melting point of the highest melting point metal powder in the powder layer for a time suiiicient to cause the powdered metals to alloy together and thereby form a strong rigid alloy structure which absorbs the soft metal coating and which is directlybonded by an alloy bond to the said metal strip, and then cooling said lined strip under nonoxidizingA conditions.

11. The steps in a continuous method of pro- 4 viding a lining of lower melting metal upon a higher melting point metal back, comprising; providing high melting point metallic strip material, distributing a uniform layer of powdered metal of. lower melting point upon the surface of said strip material, compacting the powdered metal in place upon the strip by the application of pressure, then subsequently sintering said compacted layer of powdered metal in situ upon the strip at a temperature and for a time sumcient to cause the powdered metal particles in has a higher melting point than any metal in v the compacted layer to fuse together in situ on saidstrip and simultaneously cause the sintered layer to bond to the surface of the strip, thereby greatly increasing the strength of the layer.

12. The steps in' a continuous method of fixing a-bearing lining to a strong metal supporting back, comprising; providing non-porous metallic strip material, applying a uniform -layer of powdered bearing metal upon said strip, compacting the layer of bearing metal While on the strip, then subsequently sintering said compacted layer in situ upon said strip under suitable conditions and at a temperature sumcient to cause the compacted metal particles of the bearing metal layer to fuse or alloy together and simultaneously cause the sintered metal layer to alloy bond to the metallic strip material.

13. The steps in a continuous method of making strip material suitable for use n the subsequent production of bearings, comprising, providing strong non-porous metallic supporting strip material, applying a layer of powdered metal thereon, compacting the powdered metal layer upon said strip, heating the strip with the ROLAND P. KOEHRING. JOHN M. kHJLDABOLT.

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