US 1400829 A
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OAKLEY l PRODUCTION 0F CONNECT'ING RODS `ANI) SIMILAR MACHINE PRTS.
APPLICATION `FILED MAY 29, i920.
Patented ma 2U, vMEI.,
W, w m Y M M U .M m J V. E v
JI TTUIM'EV 'I nu 30ml' OAKLEY, 0F SPRINGFIEL), 'MASSACHUSETTS ASSIGNOR TO BA'USH MACHINE TOOL COMPANYQA CGRIPRATION OF MASSACHUSETTS.
PRODUCTION OF CONNEGTINGr-RODS AN D SIMILAR MACHINE PARTS.
l T all whom it 0mg concern.'
Be it known that l, JOHN OAKLEY, a citi- `Zen of the Kingdom of Great Britain, and
resident of Springfield, Massachusetts, have invented certain new and useful Improve-y ments in the Production of Connecting-Rods and Similar Machine Parts, of which the following is a specification.
My invention provides an improved'connecting rod or similar machine part having a rotary or oscillatory connection with adjacent parts of the machine and subjected to various strains in use, and is directed particularly to the connecting rods between the pistons and the cranks of an automobile or similar internal combustion engine; the improvement' being in the composition of such rods and in their combination with other parts.
For many years aluminum and alloys thereof have been used to a greater or less extent, but no such alloy has been thought to be adapted for use in the making of connecting rods and the like, having the necessary physical qualities to make a connecting rod which should be strong enough to stand the shocks and strains of use and which could be readily machined to the accuracy required in practice. I have found that there are certain alloys of aluminum which by an -appropriate method of manufacture and treatment can be made into connecting rods which will have the durability and strength of steel andl will be very vmuch lighter with little or no increase in cost of the finished article, taking into consideration the great l saving in the cost of cutting or machining.
i ordinary l have found also that such metal is peculiarly useful in that it can be used without babbitt-ing its hearings on the wrist pin and crank pin, being itself a good bearing metal with a hi her resistance to abrasion than abbitt metal. rlhese qualities make such a connecting rod greatly desired @for automobiles where lightness is of importance in proportion of strength.. The connecting rods in automobiles are sub]ected at each operation to a downward blow 4at their upper ends from the sudden expansion in their cylinders and to an upward blow from the crank pins against the resistance of the gas to be compressed, and being of considerable length they are liable also to the bendving strain on a columnar structure. Thus they have to be made strong and of a considerable cross-section. so that a reduction in Specification of Letters Patent. Paintgd Digg, '20), 1:92p
.application med may 2a,
1920. .Serial No. 385,174.
the unit weight of the metal employed means a considerable reduction in the total weight. When we add the comparatively frictionless bearing quality of the metal it will be seen useful in producing a good polished wearing surface. This alloy is cast into ingots, worked as by rolling or` forging into billets and then cut and further forged, preferably drop-forged,- into blanks. Such forging or' otherwise working of the metal increases its tensile strength (which measures its resistance to bending) as, for example, from 27,000 pounds per square inch to 36,000 or as high as 40,000 pounds.
The forged blanks are then'heated to a temperature approximating' 500 to 525 degrecs centigrade and then quenched. lt is found that this heat treatment increases the physical qualities very substantially. `For example, alloy having beforehand an ultimate tensile strength of 36,000 pounds per square inch, will have its strength increased to 55,000 or 60,000. The elastic limit will be raised from 25,000 pounds per-square inch, to 36,000, the. elongation from 2 to 20% and the reduction of area under strain from 6 to 40%. rlFhere is thus produced a metal having the strength of steel with the comparatively frictionless quality of good bearf the ends to fit their pins. The aging of the metal after the heat treatment serves also to bring it to a condition in which it machines or cuts better than before. The mach'ining may be done before the aging is complete lbut it can. be done better afterward. The ease with :which the metal can be machined is an importantconsideration in -economy -of the product. metal itself costs several times as much as Although the I steel, yet the machining operations `on a connecting rod will cost so much more for steel than for this improved alloy as to bring the total cost of manufacture of the alloy con.
necting rod to a point which makes it a commercial compet-itor of a lsteel rod.
There areconsiderable variations possible in the composition of the aluminum alloy and in the proportions of' the components. The important thingfis to use such an alloy as will be capable of transformation by hea treatment into a metal of comparativel.A high strength, and elastic limit, though it consists chiefly of `aluminum and weigh little morethan aluminum.
The aluminum alloys above referred to andthe heat treatment thereof have been for connecting rods or any similar machine parts, although throughout this period numerous efforts have been inade especially in the automobile industry tc, lighten the en-l gine and to cheapen it by a reduction in the cost of bearings.` l .I have found by experiment that the connecting rods for such engines made as above described have notonly the knownfiqualities of lightness and strength but alsoa quite unexpected resistance to bending undenthe shock of `compressive 'strains and a resistance to abrasion and a smoothness or lack of friction which `make them not only practicable but very much superior to connect# ing rods of steel; and the economy involved -in Amachining operations has been unexpectedly great and sufficient to make them a commercial success.
Another. feature of unexpected but'considerable importance is the silence with which -they work in' engagement with the pins at either `end. It is a common criticism of automobile engines, that, especially after a short. period of use7 the wear of the pins or of their' bearings in the connecting rods causes a tapping in the en ine. With my improved connecting rods t e noise of engagement fof the parts is very greatly less than with other metals. i
The best results have been obtained with an excessive working of the alloy in making the billet or, the blank, and the alloy referred to lends itself advantageously to such operations. For example, in the making of the'connecting rods referred to I have rolled and forged the metal down to one-thirdor one-fourth of the original cross-section. This has produced a dense, tough, fibrous structure excellently adapted for use in con-v necting rods and similar parts and well capable of being cut readily by ordinary steel cutters which could not possibly be used'lfor cutting hardened steel. i
T he accompanying `drawings illustrate a connecting rod made in accordance with my invention, Figure 1 being a side elevation A with the yends Ain section and Fig. 2 being a transverse longitudinalsection. n
The connecting rod is formed withthe usual web 1 and flanges 2 and boss 3 at' its upper end apertured to receive the wrist pin 4 connected to the piston of the engine. At its lower end is a larger boss 5 with flanges 6 for attachmentto the flanges 7 of a cap "8, the boss and cap being bored to provide a circular opening for the crank 9.
The pins 4 and 9 are indicated as of steely but they may be made of VAother metal and even of the same aluminum alloy as the connecting rod, it being a peculiarity of this alloy that the friction between two`pieces of the same -allcy is no greater than it is between this alloy and steel; contraryto thev general rule that friction is greater between two pieces of the samemetal than between two pieces of different metals.
` The cap 8 is preferably made of the same aluminum alloy as the connecting rod proper, asl indicated .on the drawing, but
'this cap also may be made of other metals.
The hub 3 is bored toa closeV working t for the pin 4, without the intermediation of the babbitt or bearing metal usually linterposed between such parts in the better class of machines. I fhave foundthat with thisA aluminum alloy the. bore can be made very exact and smooth and the bearing end of the rod can oscillate on' the pin with thesame ease as a well babbitted bearing. Any usual or suitable arrangement of oil grooves may be provided. The lower end of the rod has a similar bearing fit on the crank pi11` and permits the same smoothand easy rotation of one part' with relation to theother; Even when the parts'wear in use suiiiciently to produce a slight play of the pins in their bearings, the contact of the pins with the rod of this alloy will be found to make less noise than in the case of most similar bearings.
'In the manufacture of this connecting rod the rough forging will be of excessive size so as to permit the planing and boring to exact dimensions and finish on those faces where an exact fit or a smoothfnish is dethe bosses 3 and 5 and the interior bores-of these parts and preferably also the outer faces and edges of the flanges 2. For the sired; such for example as the end faces of cap 8 the interior-bore and the bearings for the` bolts and nuts and also the side edges, (right and left edges in Fig. 2) should be machined to an exact dimension. And the meeting faces of the boss 5 and the lcap l8 should also be finished exactly. All these machining operations are accomplished With the greatest ease with this aluminum alloy; and thereby a great saving in cost is effected as compared with similar operations on steel connecting rods.
An important advantage of the use of this connecting` rod for engines is the extremely smooth and rapid acceleration and retardation of the engine and of the rapidly reciprocating parts thereof, owing to the lessened inertia and momentum by the great elimination of dead weight; such elimination being as highl as 6() or 'TO per cent. over connecting rodsand similar reciprocating parts' now commonly used.
Though l'have described with great particularity of detail aspecific design of connecting rod and a particular composition and method of manufacture, yet it will beV understood that the. design may be varied may be departed from by those skilled in the art Without departure from the inven,- tion vas defined in the following claims.`
What I claim is: v f
1. A connecting rod or lthe like made of an' aluminum alloy of the class described consisting mainly of aluminum so as to be approximately as light as this metal and which has been Worked and heat-treated to increase its density, tensile strength and elastic limit.
2. A connecting rod or the like made of an aluminum alloy of the class described consisting mainly of aluminumso as to be approximately as light as this metal and which has been Worked and heat-treated to increase its density, tensile strength and elastic limit, in combination With a pin having a bearing in one end of said rod and which has been Worked and heat-treated to increase its density, tensile strength and elastic limit, in combination with a cap of the same alloy Worked and heat treated in the same vay, the contacting faces of thel rod and cap respectively being machined to a perfect fit on each other.
Il. A connecting rod or the like composed of analuminum alloy of the class described, forged and heat-treated' and then machined.
5. A connecting rod or the like composed of an alloy including aluminum, magnesium, manganese and copper and comprising about 94% aluminum and about 0.5% magnesium, which alloy has been subjected to excessive Working and has been heated to a temperature approximating 500 to 525 degrees centigrade and then quenched and machined. A
6.' A connecting rod` for connecting vthe pistons of internal combustion engines to the cranks thereof and having bearings at its ends for engagement with a ivrist pin and a crank pin respectively, said connecting -rod being made of an aluminum alloy of the class described consisting mainly of aluminum so as to be approximately as light as this metal and which has been worked vand heat-treated to increase its density, tensile strength. and elastic limit.
ln witness whereof, lf .have hereunto signed my name. l