AU463512B2 - Composite heavy-duty machine element and method of making thesame - Google Patents

Description

37,041/71 This invention relates to a composite

heavy-duty machine element and a method of making

same. Heavy-duty machine elements which are subjected to high

loads or stresses have hitherto been formed as forgings from high

cost nickel-content alloys which in themselves are very expensive and which consequently cause such machine elements made therefrom

to be likewise very expensive. Nevertheless, in such machine elements only a portion thereof is ordinarily subjected to concen

trated heavy loads, torques or stresses which require the use of high performance alloys, yet the formation of the entire machine

element from such high performance alloys has hitherto been nece-

ssitated, requiring high cost forging operations in its productio

The:'present invention overcomes these prior disadvantag

by providing heavy-duty machine elements wherein the working por-

tions subjected to heavy or concentrated loads, torques or other stresses are formed from sintered powdered high-performance alloy

whereas the remaining portions not so loaded are formed from

sintered powdered low-performance metals. The two portions are bonded to one another inseparably as a result of their being sintered together especially if the sintering is followed by the additional step of hot forging. As a result, the quantity of hig cdst, high-performance alloy in each machine element is greatly

reduced in comparison with the same machine element forged from

solid high-performance alloy throughout, with a corresponding reduction in the ultimate cost of the finished machine element

as well as a conservation of nickel and other expensive metals.

At the same time, the heavy-duty performance capability of the

composite machine element is preserved without entailing the high cost previously accompanying the production of forged unitary hig:

performance machine elements. Moreover, test specimens made acco

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37, 041/7' ing to this invention and subjected to tensile strength tests in tension testing machines show that rupture of such specimens occurs

at locations spaced away from the junctions between the two metals

and not at such junctions.

According to the invention therefore there is provided a composite heavy-duty machine element comprising an annular mounting

member of inexpensive low-performance sintered powdered metal

particles, and an annular working member of high-performance

sintered powdered metal alloy particles disposed in co-axial sur-

face-to-surface engagement therewith and both members being hot-

forgedly densified into substantially non-porous condition and

thereby secured thereto in interlocking-particle relationship

at the junction therebetween.

Another aspect of the invention refers to a method of making a composite heavy-duty machine element comprising confin- ing a first annular mass of low-performance powdered metal particles in an annular enclosure, confining a second annular mass of high-

performance powdered metal particles in said annular enclosure in

coaxial surface-to-surface engagement with said first annular mass to form a composite annular mass, simultaneously compacting said first and second annular masses in said enclosure, sintering said

first and second annular masses simultaneously while joined to

one another in said composite annular mass and densifying the composite compact of said masses into substantially non-porous

condition by hot forging said masses of said composite annular

mass into inseparable engagement with one another subsequent to

said sintering.

Reference will now be made to a preferred embodiment of the invention as discussed in relation to the accompanying drawings.

2 4635,12

37,04 1 /71 In the drawings,

Figure 1 is a central vertical section through the die cavity of a briquetting press

showing the filling thereof with low-cost base

metal powder for the production of a face gear;

Figure 2 is a view similar to Figure 1 but with the lower punch moved downward and the

resulting space filled with high-performance

alloy powder;

Figure 3 is a View similar to Figures

1 and 2 but showing the composite powdered

metal charge in the die cavity being compacted

into a briquette;

Figure 4 is a central vertical

section through the composite powdered metal

blank obtained after sintering the briquette

4635,12

37,041 71 shown in Figure 3; Figure 5 is a central vertical section, partly in side elevation, through a deforming die set showing the sintered com- posite powdered metal blank of Figure 4 at the end of its deformation into a face gear, with the tooth-forming upper punch lowered; Figure 6 is a view similar to Figure but with the tooth-forming upper punch raised and with the original shape of the blanktAown in dotted lines; Figure 7 is a top plan view of the face gear obtained as a result of the operations shown in Figures 1 to 6 inclusively; Figure 8 is a central vertical section taken along the line 8--8 in Figure 7; Figure 9 is a central vertical section through the die cavity of a briquetting press showing the initial filling of the peripheral portion of the die cavity with high-performance metal powder outward of an annular divider or partition during formation of a spur gear briquette; Figure 10 is a perspective view of the divider or partition shown in Figure 9; Figure 11 is a view similar to Figure 9 but showing the central portion of the die cavity filled with low-performance powdered base metal; Figure 12 is a view similar to

4635,12

37,041 /7 Figure 11 but showing the removal of the

divider or partition;

Figure 13 is a view similar to Figures

9, 10 .and 12 but with the upper punch lowered

to compact the composite powdered metal charge

into a composite briquette; Figure 14 is a top plan view of the

composite heavy duty spur gear formed from the

briquette shown in Figure 13, after being

sintered into a blank;

Figure 15 is a central section through

the composite spur gear of Figure 14 taken along

the broken line 15--15 therein;

Figure 16 is a central vertical section

through the die cavity of a briquetting press

showing the inner portion of the die cavity

filled with high performance alloy powder and

the outer portion thereof filled with low

performance base metal powder, the two portions

being separated from one another by an annular

partition or divider similar to that shown in Figures 10 and'11, prior to the removal of the

partition before compacting the composite powdered

metal charge into a composite briquette suitable,

after sintering, 2r the outer race of a ball

bearing assembly;

Figure 17 is a central vertical section

through the composite inner race of a ball

bearing assembly formed similarly to the outer

race shown in Figure 16, but with the positions

6 4635.12

37,041 71

the of the alloy powder and base powder reversed so as to place the race, the high performance alloy portion on the outer side of in a subse- ball grooves being formed by cutting and/or grinding quent operation; and

Figure 18 is a central vertical section through a ball inner sintered bearing assembly employing the composite outer and powdered metal races of Figures 16 and 17. 8 Referring to the drawings in detail, Figures 1 to invention, of inclusive show the preparation, according to this designated a composite heavy-duty bevel face gear, generally or core por- (Figures 7 and 8) as consisting of an annular hub such as tion 32 of low performance sintered powdered material, by sinter- sintered powdered iron, to the face of which is bonded, toothed ing or by the additional step of hot forging, an annular powdered alloy peripheral portion 34 of high performance sintered relat- metal described below, the teeth 36 being inclined outward

ively to the axis of the gear 30. The hub or core portion 32 the latter forms the supporting portion of the gear 30 by which is not subject- is mounted upon its driving or driven element, and peripheral ed to the concentrated stresses and loads as is the one another toothed portion 34. The teeth 36 are separated from

by their respective tooth spaces or grooves 38. In the production of the bevel ring

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37.041 /71 gear or face gear 30 of Figures 7 and 8, there

is employed a conventional briquetting press

generally designated 40, of which only the

working parts adjacent the die cavity 42 are

shown. These parts are the die 44 with its

die bore 46 forming the outer boundary of the

die cavity 42, the tubular lower punch 48

being adjustably movable upward or downward

within the di.e bore 46 and having an annular

top or upper surface 50 and a central bore 52.

Mounted within the bore 52 of the tubular

lower punch 48 is a core rod 54 having an

external cylindrical surface 56 forming the

inner boundary of the die cavity 42. The

die 44 and core rod 54 ordinarily have sub-

stantially flat upper surfaces 58 and

respectively. Kovable upward and downward

within the die cavity 42 is a tubular upper

punch 62 having cylindrical outer and inner

surfaces 64 and 66 respectively and a lower

end 68 provided with alternating radial teeth

67 and grooves 69 shaped to form in the compact

or briquette the tooth profile and intertooth

spaces desired, the surfaces 64 and 66 snugly but slidably engaging the die and core rod

surfaces 46 and 56 respectively while the

toothed lower end 68 performs the pressing

operation with the top surface 50 of the lower

punch 48 serving as a temporarily stationary

abutment. The upper punch 62 is customarily

8 4 63 12

37,041 /7 connected to and movable by a press platen which in turn is moved upward or downward

by a hydraulic piston or mechanically .by a

connecting rod actuated by a crank on a

crankshaft which is rotated by an electric

motor (these conventional press parts not

shown). Prior to performing the first step

in the process bf the present invention, let it

be assumed that the top surfaces 58 and

of the die 44 and core rod 54 are in the same

plane and that the lower punch 48 has been

moved downward until its top surface 50 is

located at the desired depth for the die

cavity 42.. The operator.then operates the

press 40, filling the conventional filling

shoe thereof (not shown) with low-performance

metal powder such as powdered iron or low-

carbon steel. He then moves the filling shoe

across the top surfaces 58 and 60 of the die

44 and core rod 54 over the top of the die

cavity 42, consequently filling the die cavity

42 with an initial charge 70 of low performance

metal powder whereupon the filling shoe is then

retracted. Having performed the initial fill of the die cavity 42 with the initial low-

performance powdered alloy charge 70, the

operator now actuates the mechanism of the

press 40 to lower the upper surface 50 of

-9 4635,12

370 4/71 the lower punch 48 to a new and lower level

(Figure likewise causing the low-performance

powdered metal charge 70 to descend correspond-

ingly in the die cavity 42. The operator

then fills the filling shoe with a final charge

72 of high performance alloy powder capable of

sustaining abnormally high or concentrated

stresses or loads, and causes the shoe to move

across the top surfaces 58 and 60 of the die 44 and core rod 54 over the top of the die cavity

42, consequently filling the die cavity 42 with a final charge 72 of high performance alloy

powder, whereupon the filling shoe is again retracted. Such a high-performance alloy may

consist,for example, of the so-called "S.A.E.

4600" modified alloy, the standard composition

of which is ordinarily as follows: 0 to 0.25A Mn.

1.75 to 2.0074 Ni. the remainder being b Fe. Mo. 0.35 to 0.60A The standard 4600" alloy of which the above is a modification has the

following composition: 0.45 to 0.65% Mn. 1.65 to 2.001 li. The remainder 0.20 to 0.30 Mo. being Pe.

0.20 to 0.35 Si. The silicon component is omitted in the modified

alloy because silicon is detrimental to the

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37.041/71 working life of a die set. It is ordinarily

inserted in the above standard alloy in order

to increase the fluidity of the molten alloy

during the casting of intricate shapes.

The operator now sets in motion

the press platen operating mechanism to cause

the platen (not shown) and the tubular upper

punch 62 thereon to move downward into the

die cavity 42 (Figure compressing therein

the composite powdered metal charge 74 into

a composite briquette or compact 76 with

radial teeth 77 and tooth spaces 78 on its

upper side and with a bore 79 formed by the

core rod 54. A pressure of 25 to 35 tons per

square inch is employed, depending upon the

density desired for the composite briquette

76. The composite compact or briquette 76 is

then ejected from the die cavity 42 by moving

the lower punch 48 upward and is sintered in a

non-oxydizing or reducing atmosphere, such as

hydrogen, in a conventional sintering oven

at the usual times and temperatures familiar

to those skilled in the powder metallurgic art.

The sintered composite powdered metal blank

(Figure 4) with its face teeth 67 and tooth

space 69 thus produced is removed from the

furnace with its low performance component

82 firmly and inseparably bonded to its high

performance component 84.

To form the bevel ring gear 30 from

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37041/7 the composite sintered powdered metal blank

the latter is placed in the die cavity 86 (Figure

of th-ie die 88 of a forming die set 90 having

a tubular punch 92 with multiple circumferential-

ly-saced radial tooth-profile-formiing projections

94 and tooth spaces 95 arranged at obtuse angles

to one another around the lower end 96 thereof

and siaped substantially the sarae tooth profiles

and tooth spaces as the teeth 77 and tooth spaces

78, so as to mate with the teeth and tooth spaces

on the blank 80. The die 88 has a central bore

93 therein. The operator now operates the form-

ing press mechanism to cause the forming die

punch 92 to move downward into the die cavity

86 (Figure whereupon the tooth-forming

projections 94 deform the toothed upper face of

the upper high performance portion 84 of the

composite blank 80 into the multiple teeth 36 and

their respective intervening tooth spaces or grooves

38 while at the saiae time bending and thus de-

forming the rim of the blank 80 outward into the.

die cavity 86 to produce the bevel face gear

with its outwardly-inclined teeth 36 (Figures 7 and 8).

The composite heavy-duty spur gear

100 (Figures 14 and 15) is formed in the uanner

shown in Figures 9 to 13 inclusive likewise

employing a briquetting press 40 siuilar to that

shown in use in Figures 1, 2 and 3 hence similar parts

12- 4635,12

37 041 7i are designated with the same reference numerals.

The spur gear 100 consists of an annular hub or

core portion 102 of low-performance sintered

powdered material, such as sintered powdered iron,

to the periphery of which is bonded, by sintering,

an annular toothed peripheral portion 104 of high-

performance sintered powdered alloy.metal such as

that previously described above for the peripheral

portion 34 of the bevel ring gear 30 of Figures 7

and 8. The hub or core portion, as before, forms

the supporting portion of the gear 100 by which the

latter is mounted upon its driving or driven element,

such as a shaft (not shown) and is, as before, not

subjected to the concentrated stresses and loads as

is the peripheral toothed portion 104. The teeth 106'

in the peripheral portion 104 are directed radial-

ly outward and are separated from one another by

their respective tooth spaces or grooves 108. The

hub or core portion 102 contains an axial shaft bore 110 formed by the core rod 54. To form the

teeth 106 and tooth spaces 108 of the spur gear 100, the die cavity 42 of the die 44 is provided with correspondingly shaped radial recesses 109 and ridg- es 111, with which mate correspondingly-shaped radial teeth 113 and tooth spaces 115 on the lower end of the.upper punch 62. In the production of the spur gear 100 of Figures 14 and 15, the briquetting press 40 is operat- ed in a manner similar to that described above by lower- ing the lower punch 48 so that its upper surface

13 4635,12

37,04 1/7 is disposed at the desired depth of die cavity 42.

The top surface 60 of the core rod 54 is positioned

in the same plane as the top surface 58 of the

die 44. A tubular divider or partition 112

(Figure 10) of the saue height as the depth of

the die cavity 42 is now placed in the die cavity

42 resting upon the stop surface 50 and carefully

centered with respect to the axis of the die bore

46 and core rod 60. The operator then fills the

outer annular cavity portion or subdivision

114 of the die cavity 42 with high performance

alloy powder similar to that described above

until the top surface of the thus-formed high

performance alloy powder charge 116 is level

with the top surfaces 58 and 60 of the die

44 and core rod 54 respectively. The parts now occupy the relative positions and appearance shown in Figure 9. The operator now fills the inner portion or subdivision 118 of the die cavity 42 with low performance core or hub material powder to form the inner or central charge 120 a suitable material being powdered iron which term, as used throughout the present specific- ation, includes powdered low-carbon steel. Filling, as before, is carried out up to the level of the top surface 58 and 60 of the die 44 and core rod 54. The parts now occupy the position shown in Figure 11.

14 -4635,12

37,041/71 The operator now removes the divider

or partition 112 by carefully grasping it and

pulling it upward as shown in Figure 12,

thereby causing the inner and outer powder

charges 120 and 116 to settle down into contact

with one another. The operator now starts the press

platen operating mechanism to cause the platen

(not shown) and the tubular externally-toothed

upper punch 62 thereon to move downward into

and mate with the internally-toothed die cavity

42 (Figure 13) thereby compressing the composite

powdered metal charge 122 into a radially toothed

composite briquette or compact 124 as befcre,

a pressure of 25 to 35 tons per square inch is

employed, depending upon the density desired

for the composite briquette or compact 124.

The operator now causes the upper

punch 62 to be retracted upward by actuating

the press mechanism to retract the press platen,

after which he causes the lower punch 48 to

move upward and eject the composite radially-

toothed briquette or compact 124 from the die

cavity 42. The compact or briquette 76 is then

sintered in a non-oxidizing or reducing atmosphere,

such as hydrogen, in a conventional sintering

oven at the usual times and temperatures

familiar to those skilled in the powder metal-

lurgy art.

If greater precision is required for

4635.12

37.0 41 /71 the profiles of the teeth 106 of the spur gear 100 from the composite sintered powdered metal. toothed spur gear thus i,,rodu!)ced, the latter is

placed in a conventional gear grinding or cat- ting machine, which makes a finish grind or cut thereon. The spur gear 100 thus formed now has its toothed rim portion 104 of high per- formance sintered powdered alloy firmly bonded to the inner or hub ;portion 102 of low per- formaance sintered powidered metal and is then ready for use. The ball bearing assembly, generally designated 130, shown in cross-section in Figure 18 is also made by employing similar principles utilized in the making of the spur gear 100 in Figures 9 to 14 inclusive, hence a brief description is believed to suffice. The

ball bearing assembly 130 consists of An ex- ternally-grooved composite outer race 134 also of sintered powdered metal, and a set of bearing balls 136 dispaosed between the races 130 and 132 and running in the grooves there- between. In particular, the outer race 134 consists of an outer annular mounting portion 138 of low performance sintered powdered metal such as sintered powdered iron which is bond- ed, by sintering, to an inner annular portion 140 of high-perfor.-.,ance sintered powdered. alloy similar to that described above since it is this inner portion 140 that is subjected to 46351

37,041 /7 much heavier loads and concentrated stresses

than the outer portion 138. The outer portion

138 of the outer race 134 has an external

cylindrical surface 142 by which it is mounted

in a counterbore of a housing (not shown) or

sinilar structure relatively to which the

machine element mounted in the inner race 132

is caused to rotate. The inner race 132, on the other hand,

has its inner annular mounting portion 144

composed of low performance sintered powdered

metal, such as sintered powdered iron, with a

mounting bore 146 therethrough for receiving

the shaft or other machine element journaled

in the bearing 13C. The inner race 132 (Pigure

17) has an outer load bearing portion 148 of

.high-performance sintered powdered alloy such

as that described above for the reason that

it, too, is subjected to heavy or concentrated

loads and stress which are much greater than

those required to be sustained by the inner

portion 144. The outer race 134 is made in the

manner shown in Pigure 16, which in turn

follows the procedure set forth above in

connection with Figures 9 to 13 inclusive,

hence the same reference numerals are employ-

ed. As before, a tubular divider or partition

112 like that of Figure 10 is inserted in the

46 3 51

37,041/71 die cavity 42 of the briquetting press 40 and

carefully centered therein with reference to

the axis of the core rod 54 and die bore 46.

The filling of the outer and inner portions

of the die cavity 42 is,however, reversed in

Figure 16 in that the portions of the die

cavity outside the divider 112 are filled

with low performance alloy powder such as

the powdered iron described above, and the

portions inside the divider 112 filled with

high performance metal powder such as the

alloy powder also described above, thereby

producing the outer and inner charges 152

and 154 respectively. The divider 112 is

then removed in the manner described above,

and the upper punch 62 (Figure 13) is lower-

ed to compress the charges 152 and 154

simultaneously into a composite briquette

or compact (not shown) which is then sintered

in a manner described in connection with the

briquette or compact 124 of Figure 13. In-

stead of forming teeth on the composite

sintered powdered metal blank thus made,

however, an interval annular ball groove 150

of arcuate cross-section is machined therein.

The composite inner race 132, how-

ever, is forr.ed vmore nearly in the manner set

forth above in connection with Figures 9 to 13

inclusive in that the inner or mounting portion

156 thereof with the mounting bore 146 therein

4 635.1

37,041 /7 is of low performance sintered powdered metal

such as powdered iron whereas the outer por-

tion 158 is of the above-mentioned high-

performance sintered powdered allcy arranged in the saie relationship within the die

cavity 42 as in Figures 9 to 13 inclusive

and employing the same procedures with retard

to briquetting and sintering. In the inner

race 132, however, an annular ball groove 160

of arcuate cross-section is additionally

machined in the high-performance outer por-

tion 158 dislosed opposite to and facing

the ball groove 150 (Figure 18). A set of

bearing balls 136 is then inserted into the

ball grooves 150 and 160 between the outer and

inner races 134 and 132 and the bearing is ready

for use.

463 12

Claims (1)

1. 37 041/71

   THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:-

   1. A composite heavy-duty machine element comprising an

   annular mounting member of inexpensive low-performance sintered

   powdered metal particles, and an annular working member of high-

   performance sintered powdered metal alloy particles disposed in

   coaxial surface-to-surface engagement therewith both members condi- being hot-forgedly densified into substantially non-porous tion and thereby secured thereto in interlocking-particle relatic

   ship at the junction therebetween.

   2. A composite heavy duty machine element, according to

   claim 1, wherein the low-performance metal particles are powderec

   ferrous metal particles, and wherein the high-performance metal

   alloy particles are manganese-molybdenum alloy particles.

   3. A composite heavy-duty machine element, according to

   claim 1, wherein said junction is substantially cylindrical.

   4. A composite heavy-duty machine element, according to

   claim 1, wherein said junction is substantially frusto-conical.

   A composite heavy-duty machine element, according to

   claim 1, wherein said working member is disposed externally of

   said mounting member.

   6. A composite heavy-duty machine element, according to

   claim 4, wherein said working member is disposed face-to-face

   with said mounting member.

   7. A composite heavy-duty machine element, according to

   claim 1, wherein said working member is disposed internally of said mounting member.

   8. A composite heavy-duty machine element, according to

   claim 6, wherein said working member has an annular array of gea

   4635,12

   37, 041/71

   teeth thereon inclined relative to the axis of said members.

   9. A composite heavy-duty machine element, according to

   claim 8, wherein said gear teeth are inclined at obtuse angles

   relatively to the axis of said members.

   A composite heavy-duty machine element, according to

   claim 1, substantially as hereinbefore described with reference

   to the accompanying drawings. 11. A method of making a composite heavy-duty machine element

   comprising confining a first annular mass of low-performance

   powdered metal particles in an annular enclosure, confining a

   second annular mass of high-performance powdered metal particles in said annular enclosure in coaxial surface-to-surface engagement

   with said first annular mass to form a composite annular mass,

   simultaneously compacting said first and second annular masses in

   said enclosure, sintering said first and second annular masses si-

   multaneously while joined to one another in said composite annular

   mass and densifying the composite compact of said masses into sub-

   stantially non-porous condition by hot-forging said masses of

   said composite annular mass into inseparable engagement with one

   another subsequent to said sintering. 12. A method of making a composite heavy-duty machine element

   according to claim 11, wherein said low-performance powdered metal

   particles are of ferrous metal, and wherein said high-performance

   powdered metal particles are of manganese-molybdenum alloy. 13. A method of making a composite heavy-duty machine ele-

   ment, according to claim 11, including forming circumferentially- spaced gear teeth on a face

   4635,12

   37,041/71

   powdered metal of said second mass of high-performance the mass simultaneously with alloy of said composite

   compacting thereof.

   A method of making a composite heavy-duty

   machine element, according to claim 11, substantially

   the as hereinbefore described with reference to accompanying drawings.

   DATED: 24th January, 1975

   PHILLIPS ORMONDE AND FITZPATRICK Attorneys for: FEDERAL-MOGUL CORPORATION

   4635.1: