United States Patent 19 11, 3,751,080
Bailey et al. (45) Aug. 7, 1973
54 CONNECTING ROD MANUFACTURING 3,41 1,378 11/1968. Borgeaud.............................. 74/579
(75) Inventors: John M. Bailey, Dunlap, Donald G.
Zook, Metamora, both of Ill. Primary Examiner-Andrew V. Kundrat
Attorney-Fryer, Tjensvold, Feix, Phillips & Lempio
(73) Assignee: Caterpillar Tractor Co., Peoria, Ill.
22 Filed: Jan. 15, 1971 57 ABSTRACT
High quality connecting rods and similar machine com
21 Appl. No.: 106,804 ponents comprised of an assembly of two clamped to
gether parts are manufactured from tough heat treated
52 U.S. Cl. ..................... ... 287.152.03, 74/579 E high carbon steel, or the like, according to a manufac
(5) Int. Cl............................................. B60b 27/06 turing method of reduced cost. Essentially all machin
58) Field of Search...................... 74/579 R, 579 E; ing of the component is conducted on an integral piece
287.152.03; 308/74 prior to its being divided into the two separate parts by
fracturing along a frangible zone effected by electron
56 References Cited beam bombardment. The resulting irregular mating
UNITED STATES PATENTS surfaces of the respective parts have substantial resis
tance to relative sliding upon clamping of the parts to
2,553,935 5/1951 Parks et al.................. 74.1579 EUX gether.
2,371,399 31 1945 Mantle...................... 287.152.03 UX
3,285,098 l l (1966 Beveridge............................. 74.1579 3 Claims, 6 Drawing Figures
PATENTED AUG 793 3.75l,080
SHEET 1. Of 2
INVENTOR
JOHN M BALEY
DONALD G, ZOOK
2-3-227,724-75. AITORNEYS
PATENTED AUG 7973 3. 75l. O80
SHEET 2 OF 2
INVENTORS
JOHN M BALEY
}}
ATTORNEYS
3,751,080
2
CONNECTING ROD MANUFACTURING ple part component as an integral piece from high car
BACKGROUND OF THE INVENTION
bon steel and rough machining the piece to approxi
mately final dimensions, electron beam bombarding
Many machine components, such as connecting rods, the piece along a preselected path to heat the steel in
track links, journal boxes, etc., require two parts a narrow band and form a brittle frangible zone upon
clamped together by fasteners, or the like, to form a quenching, finish machining the piece to final dimen
unitary part which accepts bearing shells, shafts, pins or sions, and fracturing the piece through the frangible
the like. In the case of connecting rods the bore must ZOe.
be accurately machined and its center line generally The parts of the component thus formed have irregu
lies on or near a plane through the joint of the two adja 10 lar complementary mating surfaces which upon fasten
cent parts comprising the assembled component. ing the parts together provide a joint having substantial
Manufacture of such components usually involves resistance to relative sliding between the parts of the
casting or forging the parts separately, rough machin assembled component. -
ing the separate parts, machining the joining faces to
mate, drilling holes to accept fasteners for securing the 15 BRIEF DESCRIPTION OF THE DRAWING
parts together, bolting the mating parts together, and FIG. 1 is a front elevational view of a connecting rod
perhaps machining the bore defined by the assembled depicting manufacture in accordance with the present
parts accurately for fitting of a bearing or shaft. Alter invention.
natively, the parts are cast or forged, as an integral FIG. 2 is a side elevational view of the connecting
piece, holes are drilled to accept fasteners for securing rod.
the parts together, the piece is saw cut to obtain two FIG. 3 is a front elevational view of a modified form
parts, the half bores are rough machined, the joining of connecting rod depicting a modification in the man
faces are machined, the parts are bolted together, and ufacturing method.
the bore is machined to obtain a finished diameter. FIG. 4 is a side elevational view of a master track link
All of the steps of either manufacturing method re 25 manufactured in accordance with the present inven
quire accurate, and thus expensive machining opera tion.
tions. Hence, elimination of any of the steps results in FIG. 5 is a side elevational view of a variation of a
generally less costly, more easily made part.
With a view to eliminating some of the steps and re 30 FIG. 6track
master
is an
link.
enlarged view of a portion of a fracture
ducing the manufacturing cost, various machine com plane in accordance with the present invention.
ponents, such as connecting rods for inexpensive en
gines, generly of cast iron or nonferrous materials,
have been made by casting or forging the component
DETAILED DESCRIPTION OF THE INVENTION:
to size, machining all bores and surfaces, and then In accordance with the present invention a connect
breaking the component across the center line of the 35 ing rod is manufactured from tough, hard, high quality
bore. The parts are bolted together to provide an as metal, such as high carbon steel, with a reduced cost of
sembled component having a perfectly formed bore. manufacturing. Although the invention is specifically
This method eliminates several machining operations described with respect to the manufacture of connect
including machining of the mating surfaces and clamp ing rods, it will be apparent from the ensuing descrip
ing of the parts together prior to finish machining of the 40 tion that the invention is equally applicable to the man
bore. In addition, the many small imperfections or ir ufacture at reduced cost approximately similar multiple
regularities in the mating surfaces created by the crack part component assemblies having an accurately ma
serve to lock the parts together and prevent sliding. chined bore.
Unfortunately, high quality connecting rods and the Considering now the invention in detail with respect
like, such as are utilized in diesel engines and high out 45 to the manufacture of a connecting rod, the connecting
put gasoline engines for example, are made of a rela rod is forged or otherwise formed from high carbon
tively high carbon steel heat treated to provide a tough steel, or similar tough metal to provide a cap 11 and
ness and hardness unsuitable for breaking without ex rod 12 as an integral piece 13. A bore 14 is provided
cessive distortion of the component. Therefore, the lat 50 during the forming of the piece with its center line 16
ter cost reduction method which has been successfully lying apporximately on a desired parting plane 17 be
employed in the manufacture of various two part com tween the cap 11 and rod 12.
ponents from relatively brittle materials, such as cast The piece is then rough machined to approximately
iron, has not been applicable to tough materials, such the final dimensions of the component. In addition, bolt
as high quality steel. 55
holes 18 are drilled through the piece on opposite sides
SUMMARY OF THE INVENTION
of the bore 14 in right angular relation to the parting
plane 17.
The general object of the present invention is to pro In accordance with the particularly salient aspects of
vide a cost reduction method of manufacturing various the invention, the piece 13 is bombarded with a beam
multiple part machine components, such as connecting 60 of high energy electrons along a path exteriorly inter
rods and track links, from high quality steel or similar sected by the parting plane 17. The metal in a very nar
tough, hard material in a manner similar to that em row band is locally heated by the electron beam above
ployed with relatively brittle material conducive to the austenitic temperature of the metal and is
breaking of a finish machined integral piece to form the quenched by the surrounding cold metal to produce a
finished separate parts of the component. 65 narrow frangible zone 19 of very hard brittle steel in
In the accomplishment of the foregoing, and other the parting plane 17. In some instances, it may be desir
objects and advantages, the method of the present in able to employ a liquid or vapor quench to enhance the
vention generally includes forming the parts of a multi quenching by the surrounding cold metal.
3,751,080
3 4
It should be noted that the width of the frangible zone wise be applied to the embodiment of FIGS. 1 and 2 if
19 is a function of the depth of penetration of the im desired.
pinging electron beam. Consequently, an even nar In addition the present invention is also suitable for
rower brittle zone may be produced, if desired, by si manufacturing other types of components such as, for
multaneously directing two electron beams upon the instance, a master track link used to retain the track on
piece from the opposite sides thereof. In any event, the a crawler vehicle, or the like. One such master link
properties of the metal outside of the narrow frangible made in accordance with the invention is shown in FIG.
zone 19 of the piece are unaffected by the electron 4.
beam bombardment. Referring to FIG. 4, such a master link 36 comprises
In the accomplishment of the electron beam bom O an elongated forging having a first bore 38 at one end
bardment step of the manufacturing method, the large thereof and a second bore 39 at the other end thereof.
or bore end of the rod piece 13 is preferably placed on Bores 38 and 39 are positioned so as to accept track
a locating fixture in an electron beam welder apparatus pins (not shown) therethrough which track pins hold
of conventional design, clamped by sealed members, the opposite ends of a track (not shown) in circling re
and the small surrounding space almost instantly evac 15 lationship around the sprocket wheels and idlers of a
uated. The high energy electron beam is then passed tracked vehicle.
across the bore end of the piece along the desired path The link 36 is split into two parts 41 and 42 along the
to effect the frangible zone 19. The bombarded piece plane 43 which runs diagonally from below bore 38 to
is then removed from the electron beam apparatus. It above bore 39. The parts 41 and 42 are clamped to
has been found that the electron bombardment opera 20 gether by means of fasteners, e.g., bolts 44 which pass
tion costs less than ten cents. through one part 42 and thread into the other part 41.
With the piece 13 thus provided with the frangible It will be apparent that the master link 36 may be
zone 19, the piece is finish machined to final dimen split into two separate parts 41 and 42 by simply re
sions, including finish machining of the bore 14. This moving fasteners 44 or clamped into a single unitary
also serves to clear up any blemishes which may have 25 part or link 36 by threading fasteners 44 back into the
been produced by electron beam bombardment. clamping positions.
Finally, the piece 13 is fractured, as by impact, FIG. 6 shows a portion of the fracture plane 43 in a
through the frangible zone 19 to provide the finished greatly enlarged and exaggerated illustration. However,
cap and rod parts 11 and 12 of the connecting rod as it can be seen that the mating surface 46 of plane 43
sembly. The complementary irregularities in the mating 30 comprises a great number of microscopic ridges, teeth
surfaces produced by the fracture provide a joint hav and serrations which mate with similar irregularities on
ing substantial resistance to relative sliding between the the facing upper surface 47 of the plane 43. Such irreg
parts upon clamped assembly thereof by means of fas ularities hold both parts of the link 36 in exact align
teners 21 extending through the bolt holes 18. Such a ment under all conditions.
slide resistant joint minimizes fretting and ultimate fail 35 The link 36 is manufactured in exactly the same man
ure of the assembled connecting rod. ner as previously described with regard to connecting
Although the frangible zone 19 is sufficiently brittle rod 13 to provide the two parts 41 and 42 and their
to facilitate a suitable fracture upon impact of one of mating fracture plane 43.
the parts 11 or 12 relative to the other, in some in In another variation as shown in FIG. 5, the master
stances it may be desirable to form a stress concentrat 40 link 36 may be provided with a wavy mating plane 48
ing notch 22 circumscribing the zone. Such a notch in of the same configuration as that provided in connect
sures fracture in the frangible zone when separating the ing rod 23 illustrated in FIG. 3. In such instance, the
parts. link 36 may be provided with a number of small bores
Referring now to FIG. 3, a modification of the con 49 along the length of fracture plane 48 for the purpose
necting rod manufacture of the invention is depicted as 45 of ensuring the correct fracture of plane 48 when the
applied to an angle aplit connecting rod assembly 23. electron beam treated link is separated by the applica
Here again the cap and rod parts 24 and 26 of the as tion of pressure thereto.
sembly are integrally provided as a forged, or otherwise it will be obvious from the specific descriptions
suitably formed single piece 27 which is rough ma 50 above, that the technique of the present invention is
chined to approximately final dimensions. also suitable for components that are to be fractured
However, a brittle frangible zone 28 is produced by . into three or even more parts. Thus by selecting the po
electron beam bombardment in the manner previously sitions at which the component is bombarded with the
described to generally lie in a separation plane which electron beam, any desired configuration and number
is at an acute angle to the longitudinal center line of the 55 of fractured parts may be obtained.
rod part 26, rather than at right angles as in the en Although the invention has been hereinbefore de
bodiment of FIGS. 1 and 2. scribed and illustrated in the accompanying drawing
Of more importance, the electron beam is directed with particular reference to several preferred embodi
along an undulated path in its bombardment of the ments, same are not intended to be in any way limiting
piece 27 to effect the frangible zone 28. Thus, upon 60 upon the invention, reference being made to the ap
fracture of piece through the undulated frangible zone pended claims for a precise delineation of the true
28 subsequent to finish machining of the piece, the re spirit and scope of the invention.
sulting finished cap and rod 24 and 26 have mating What is claimed is:
wavy surfaces 29. 1. A machine component comprising an assembly of
Upon clamped assembly of the parts by means of fas 65 at least two parts of high quality metal with each part
teners 31, the wavy mating surfaces further increase having a parting line extending across the same, said
the resistance to relative sliding therebetween. It will be parting line extending into each of the parts a predeter
appreciated than an undulated frangible zone may like mined depth equal to the depth of penetration of an im
3,751,080
S 6
pinging high energy electron beam and extending fasteners disposed therein for securing said parts to
around the periphery of each of said parts and having gether.
al overall continuously smooth regularly undulating 2. The machine component of claim 1 wherein said
configuration, a stress concentrating notch having an component is a connecting rod.
apex contiguous with said parting lines when said parts 5
are brought together and radiating above and below 3. The machine component of claim 1 wherein said
said line to facilitate and insure the fracturing along component is a track link.
said line, holes disposed through said parting line, and sk k k :k
10
15
20
25
30
35
40
45
50
55
60
65
