CA1223434A

CA1223434A - Universal joint cross member trunnion and method

Info

Publication number: CA1223434A
Application number: CA000423220A
Authority: CA
Inventors: Ray A. Gall
Original assignee: Dana Inc
Current assignee: Dana Inc
Priority date: 1982-03-22
Filing date: 1983-03-09
Publication date: 1987-06-30
Also published as: ES520807A0; AR231571A1; BR8301411A; AU1233383A; ES8403056A1; AU565633B2

Abstract

ABSTRACT

An improved lubrication means for anti-friction bearing trunnion systems of the type normally having smooth and/or ground contours in universal joint assemblies includes a plurality of closely spaced lands and lubrication grooves circumferentially disposed about each trunnion. The lands provide actual bearing contact surfaces for needle roller bearings, while the grooves provide means for retention of lubrication oil between bearing and trunnion interfaces. In a preferred embodiment, the lands and grooves are uniformly and alternately spaced, and each are oriented in planes perpendicular to the longitudinal axes of the trunnions. One preferred method of making the improved trunnion includes the steps of machining and heat treating, without grinding as an intermediate or final step. Additionally, a step of roll burnishing the lands of the trunnions prior to heat treatment may be included.

Description

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Titl_ Universal Joint Cross Member Trunnion and Metho~

Back~round of the Invention ThiS invention relates to universal joint assemblies of the Cardan type which are known to include journal cross members having radially extending cylindrical tr~nnions for connecting furcations extending from pairs of rotary members. More particularly, the invention relates to an improved lubrication system for the trunnion- furcation interface, and a method of manufacture thereof.
The trunnions of such assemblies are supported generally in needle roller bearings which are in turn supported in cup-shaped bearing races which are fitted into, and which frictionally engage, respective furcations. Each race contains an annulus of such needle bearin~s, physically interposed between the inner periphery of the race and associated trunnion, so that substantially frictionless movement may take place between the trunnion and the bearing race.
Prior art trunnion members have been ground to highly polished finishes for rolling contact with needle roller bearings. Such bearing systems, variously referred to as anti-friction bearings, contain very smooth surfaces which do not satisfactorily provide for positive oil circulation during the limited oscillatory or vlbratory movements of the type encountered in universal joint operation. As will be appreciated by those skilled in this art, anti-friction bearings tend to depend on continuous revolutionary movement of the bearing members for proper lubrication. Because revolutions of bearings asociated with universal joints are only partial, a less than desirable oil circulation is achieved which results in relatively unsatisfactory joint performance.
Moreover, in dirty and/or corrosive environments, the lack of sufficient lubrication becomes extremely critical, and can often result in premature failure of the bearing trunnion system. In moisture-laden and/or corrosive environments, p, j, 1~23434 fretting corrosion can also occur to further accentuate wear and thereby accelera~e the deterioration of the - bearing-trunnion interface.
c Summary of the rnvention The¦invention disclosed herein provides an improved lubrication mean~ for anti-friction bearing trunnion systems of the type normally having smooth and/or ground contours in universal joint assemblies. A plurality of closely and/or minutely spaced lands and lubrication grooves are disposed circumferentially about each trunnion, the lands providing contact surfaces for needle roller bearings, and the grooves providing means for retention of lubricant between bearing and trunnion surfaces. In a preferred embodiment, the lands and grooves are uniformly and alternately spaced, respectively, each of the lands and grooves being oriented in planes generally perpendicular to the longitudinal axes of the trunnions. In another preferred embodiment, the lands and grooves are partially and randomly discontinuous about the circumference of each trunnion.
A preferred method of making the improved cross member trunnions includes the steps of machining and heat treating, without the typical intermediate or final grinding step. An alternate preferred method includes a step of roll burnishing the lands of the trunnions prior to heat treatment.
Brief Description of the Drawin~
Fig. 1 is a plan view, partially in section, of a cross member of a universal joint containing the improved trunnions of ~his invention, including a view of needle bearings and bearing races associated therewith;
Fig. 2 is a fragmentary view of one preferred embodiment of the improved trunnion of this invention;
Fig. 3 is a fragmentary view of another preferred embodiment of the improved trunnion of this invention:
Fig. 4 i~ a sectional view of groove and land detail of one preferred embodiment of the trunnion hereof;

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Fig. 5 is a sectional view of groove and land detail of another preferred embodiment of the improved trunnion;
Fig. 6 is a fragmentary cross-sectional view of the trunnon~needle bearing interface in a prior art universal joint; ~nd Fig. 7 is a fragmentary cross~sectional view of the same interface in a universal joint containing the improved trunnion of this invention.
Fig~ 8 is a perspective view of the cross member of this invention, depciting one preferred embodiment wherein the lands and grooves are partially and randomly diæcontinuous about the circumference of the tr~nnions.
Detailed Descr ~tion of the Preferred Embodiments _ _ _ . _ A cross member 10 of the type employed in a universal joint assembly (not shown) is depicted in Fig. 1. In the preferred embodiment as described herein, the cross member 10 includes four improved trunnions 14, each extending radially outwardly along longitudinal axes A-A or B-B of a center body portion 12. Each trunnion 14 is encapsulated by a needle roller bearing assembly 16, the latter consisting of a plurality of needle roller bearings 24 contained within a cup-shaped bearing race 22. The cylindrical body portion of each trunnion 14 contains an end portion 18 which abuts and slidingly engages a mating thrust surface 20 within each bearing race 22. The bearings 24 are free to rotate within a bearin~ cavity B, defined by an annular space between the interior cylindrical surface of the bearing race 22 and the exterior cylindrical surface of the trunnion 14. An elastomeric friction ring 26 is supported in each bearing race 22 to ensure proper radial positioning of the needle roller bearings 24, as will be understood by those skilled in the art. Annular elastomeric sealing members 28 operate to protect the bearings from external dirt and other contamination. The members 28 also aid the retention of lubricant within the bearing cavity 8.

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A fragmentary view of a preerred embodiment of the improved trunnion 14 of the cross member 10 is shown in Fig.

2. The trunnion 14 con~ains alternately spaced lands 30 and grooves~32 for providing improved oil retention over the cylindr~cal surface of the trunnion 14. Lands 30 and grooves 32 are particularly iden~ified with suffixes A, B, C, and D in Figures 2, 3, 4, and 5, respectively, for distinction purposes only. Figs. 4 and 5 more specifically point out two preferred embodiments of the lands 30 and grooves 32, respectively. In both embodiments, grooves 32 provide oil passages or troughs for lubricating the trunnion lands 30 and the needle bearing members 24 which roll thereon, as the lands 30 define the actual bearing roller contact surfaces between the trunnion 14 and the needle bearings 24. The grooves 32 of Fig. 4 represent an embodiment formed by a machine tool, for example as by a lathe or milling operation. The groove 32 of Fig. 5, however, depicts an embodiment also formed by such a tool, but in which a subsequent roll burnishing operation has been performed to create a projection 29 on either side of the groove 32 which slightly overlaps the bottom 27 of the groove.
It wiIl be appreciated by those skilled in the art that the needle roller bearings 24 do not traverse the entire periphery of the trunnion in the evironment of a universal joint.
Referring to Fig. 6, it will be seen, for example, that the needle bearing 24 as shown therein will move from the po_ition shown at 34 to that as shown at 36 and back to 34 in an oscillating movement, and thus over a fairly localized surface portion of the trunnion 14. Under such movement, if the mating surfaces are smooth, as for example where they have been finely ground, the lubricant 38 will tend to be forced outwardly of the path defined between points 34 and 36, resulting in a contact area therebetween prone to becoming ~tarved of lubrication. On the other hand, it is well known that in most

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anti-friction roller bearing environments a roller 24 will make complete revolutions relative to a member 14 whereby an oil wave 38 remains continouously in motion about the circular member 14. As a result, the smoothly ground surfaces in most anti-fr~ction roller bearing environments are not as prone to localized oil starvation problems~
As this invention relates to proper lubrication under oscillatory or vibratory movement, it will be seen in Figs. 2 and 3, the preferred embodiments of this invention, that the lands 30 define rolling contact surfaces for the needle bearings, and each of the lands 30 and grooves 32 are oriented in planes which are generally perpendicular to the axes of the trunnions 14. In Fig. 2, the lands and grooves 30 and 32, respectively, define individual annular paths about each of the cylindrical trunnion bodies. In the embodiment of Fig. 3 however, the lands and grooves lie on helical paths about the cylindrical trunnions 14. In both instances, the preferred embodiments of each land and each groove are such that each land is equidistant from its next adjacent land and each groove is equidistant from its next adjacent groove.
Referring now to Fig. 7, it may be more fully appreciated that the lubrication of the contact area between the trunnion 14 and needle bearing 24 is substantially improved between oscillation points 34 and 36 by the addition of the grooves 32. Thus, in Fig. 7, the lubricant 38 will not wash away from the contact path extending between points 34 and 36, but will instead be retained within the grooves 32 between the latter contact points. The depth of the grooves 32 is represented by the space between the bottom of the groove 32, shown as an arc 40, and the top of the land 30, shown as an arc 42. By contrast, the smoothly ground cylindrical contact areas between both the trunnion 14 and roller 24 in the prior art interface Of Fig. 6 will create the tendency for the lubricant to wash 3 A/~ 3 ~

away from the contact path between points 34 and 36 along the smoothly ground contact arc 41 of the trunnion 14.
A preferred method of forming the lands 30 and grooves 32 in the trunnion involves rough machining, and then heat treatin~ the trunnions, without intermediate or final grinding ~-and/or ~olishing steps. The cross members are generally metal forgings, but may alternatively comprise metal castings, as will be appreciated by those skilled in the art~ The machining is preferably achieved at cutting speeds in the range of 400 ~o 600 revol~tions per minute. The feed rates of the machine tool are preferably in the range of 15 to 20 thousandths of an inch per revolution. Preferred cutting depths are in the range of 60 to 90 thousandths of an inch.
A machining operation conducted at the preferred feed rates and cutting depths herein noted will effectively achieve a roughly turned surface in a typical metallic trunnion member, as will be appreciated by those skilled in the art. In the helical embodiment of Fig. 3, such surface may be achieved by a constant tool contact over the total longitudinal axis of the trunnion body. Characteristic of the preferred machining parameters is a tendency for the tool to occasionally cut the lands 32 and grooves 32 in a partially and randomly discontinuous manner about the circumference of each trunnion, thus exhibiting an appearance as shown in Fig. 8. ~he discontinuities produced, however, are not disruptive of the improved lubrication feature of the invention. At this point, as was mentioned in connection with Fig. 5, an optional roll burnishing step may be performed by a rolling member which penetrates the lands at a surface depth preferably in the range of 5 to 10 thousandths of an inch.
The preferred heat treatment step includes carborizing the trunnions in a nitrogen atmosphere at approximately 1650 to 1750 F., then quenching the trunnions in oil.

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The invention as described herein provides a substantially improved lubrication mechanism for trunnions and associated needle roller bearings for use in universal joint assemblieS.
Alterna~e configurations are seen to fall within the appended claims,~and benefits other than oil retention on the trunnion surface area are envisioned.~ For example, the annular grooves may also provide for retention of corrosion and other debris particles from the mating surfaces. The latter would operate to reduce deleterious effects produced by the presence of such 1~ particles along the contact interface of the rolling members.
Also, for example, the lands and grooves might alternatively be formed in the interior cylindrical surface of the bearing race 22.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of making a cross member of a universal joint, said cross member defining radially extending cylindrical trunnions disposed for engagement with furcations of a pair of rotary members, each of said trunnions comprising a plurality of axially spaced lands and grooves circumferentially disposed thereon, comprising the steps of:

(a) rough machining said lands and grooves on said trunnions; and (b) heat treating said trunnions.

2. The method of claim 1 further comprising an additional step of roll burnishing the lands in said trunnions prior to the step of heat treating said trunnions.

3. The method of claims 1 or 2 wherein said machining step is achieved at cutting speeds in the range of 400 to 600 revolu-tions per minute and feed rates in the range of 15 to 20 thousandths of an inch per revolution.

4. The method of claim 2 further comprising a machining cut depth in the range of 60 to 90 thousandths of an inch and wherein said roll burnishing step is achieved by a rolling member penetrating said surface at a depth of 5 to 10 thousandths of an inch.

5. The method of claim 4 wherein said heat treatment step comprises carburizing said surface in a nitrogen gas atmosphere at a temperature in the range of 1650 to 1750 degrees Fahren-heit, and then quenching said surface in oil.

6. The method of claim 1 wherein the cross member of the universal joint comprises a bearing surface.

7. The method of claim 6 further comprising an additional step of roll burnishing said bearing surface prior to the step of heat treating.

8. The method of claim 6 wherein said machining step is achieved at cutting speeds in the range of 400 to 600 revolutions per minute, and feed rates in the range of 15 to 20 thousandths of an inch per revolution.

9. The method of claim 8 further comprising a machining cut depth in the range of 60 to 90 thousandths of an inch and wherein said roll burnishing step is achieved by a rolling member penetrating said lands at a surface depth in the range of 5 to 10 thousandths of an inch.

10. The method of claim 9 wherein said heat treatment step comprises carburizing said trunnions in a nitrogen gas atmosphere at a temperature in the range of 1650 to 1750 degrees Fahren-heit, and then quenching said trunnions in oil.