US2719064A - Conical self-adjusting bearing - Google Patents

Description

Sept. 27, 1955 J. R. BARNARD CONICAL SELF-ADJUSTING BEARING Filed Dec. 1l, 1952 0 if ww 3 4 o 4 6 6 :u w HMV 9 M 5 5 fr m o 5 ,3 M 6 M5 743 w, .WL v L figg Z wfg' IN VEN TOR. JOHN l?. BRNARD BY ffwmv/y ATTORNEYS United States Patent CONICAL SELF-ADJUSTING BEARING John R. Barnard, Lansing, Mich. Application December 11, 1952, Serial No. 325,326 Claims. (Cl. 308-70) This invention relates to a new and improved bearing structure in which the running clearance of the bearing is automatically adjusted in accordance with the speed of the rotatable part and in a manner to decrease the clearance as the speed reduces and to increase the clearance as the speed increases.

In the manufacture of machine tools for precision work it is imperative that lateral play of the tool spindle under different operating conditions be prevented because any variation in the position of the tool with respect to the work elects the size thereof. This is especially true in grinding operations where the accuracy requirements are greater than in most other types of machine tools. In centerless grinding machines, the forces acting are peculiar in the sense that the regulating wheel is not only subject to a force laterally of its axis but also to a continuous thrust in one direction parallel to its axis. In addition, the regulating wheel, which is in reality an abrasive grinding Wheel, has to be dressed or trued While running at a relatively high speed to attain the best results, but, in grinding operations, it runs at relatively slow speeds. Therefore, the bearing structure must be of such a nature that the wheel will be maintained concentric to the same axis whether running light at high speed without axial thrust, as it does when running slow under load and with a continuous axial thrust thereon.

This invention therefore contemplates a spindle bearing construction having a thrust resisting characteristic; and a radial bearing characteristic which is adjustable automatically as respects tightness or looseness of the running parts so that under relatively high speed andno lateral load or thrust the running member will seek the same center of rotation that it does when running slow. It should be obvious that satisfactory results cannot be obtained if the wheel rotates about one center when being dressed and about another center during a grinding operation.

One of the objects of this invention is therefore to provide a bearing that will automatically adjust itself in accordance with its rate of rotation to vary the running clearance between its relatively rotating parts and thereby accurately maintain its axis of rotation'in the same position regardless of load conditions.

Another object of this invention is to provide an improved automatically adjustable double conical bearing in which the cones are automatically shiftable axially to vary the running clearance in the bearing.

A further object of this invention is to provide a conical bearing construction which is automatically adjusted hydraulically and in which the adjustment is automatically controlled or responsive to the rate of rotation of the parts. f

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompaying drawings forming a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, .withice in the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Referring to the drawings in which like reference numerals indicate like or similar parts:

Figure 1 is a vertical sectional view representing one embodiment of the invention.

Figure 2 is a view similar to Figure l showing a second embodiment of the invention.

Fig. 3 is a fragmentary sectional view taken on line 3 3 in Fig. 2, looking in the direction of the arrows.

Referring to the drawings, the reference numeral 10 indicates a housing for supporting a spindle 11, which may be, for example, the regulating wheel spindle commonly found in centerless grinding machines. One of the functions of the regulating wheel of a centerless grinding machine is to impart a feed component to the work piece and thereby cause the work piece to automatically feed past the grinding Wheel to effect the grinding operation, and since this feed component s parallel to the axis of the work it necessarily causes a reaction thrust on the regulating wheel spindle axially thereof, and this reaction is ,continuous as long as work is being ground. It is, therefore, necessary that in providing proper bearing for a regulating wheel spindle that the question of axial thrust be considered.

Another function of the regulating wheel is to drive or rotate the work, and this is accomplished by maintaining the wheel in frictional contact with the periphery of the work and simultaneously pressing the work against the grinding wheel which, in turn, produces a lateral force reaction on the regulating wheel spindle.

It is, of course, necessary to maintain the regulating wheel sharp to function properly as a driving member for rotating the work, and this condition is maintained by intermittently dressing or truing the regulating wheel. Since the regulating Wheel is usually of the abrasive grinding wheel type, best results are obtained in the dressing operation by rotating the wheel at what is known in the art as a truing speed, which is approximately ten times that of the normal working speed of the wheel during a grinding operation.

Thevmanner of constructing the bearing to take care of this widely divergent condition will now be explained.

In the construction shown in Figure l, the housing 10 has a bore 12 in which is tted a sleeve 13 having an outward flange 14 on one end by which the sleeve is positioned axially and is secured in position by a cover plate 15 fastened to the housing by suitable screws 16. The sleeve has an inward flange 17 at the other end against which is positioned a conical member 18 and held against rotation with respect to the sleeve by a locking pin 19. A second conical member 20 is mounted in the other end of the sleeve and held against rotation by a locking pin 21 carried by plate 15. In the tapered bores of the conical bearing members 18 and 20 are conical journal members 21' and 22 respectively, and these members are supported on the cylindrical portion 23 of the spindle 11 for axial sliding movement relative thereto, but are keyed for rotation with the spindle by a key 24 which is mounted in a key slot 25 formed in the cylindrical portion 23 and having its ends fitted in key slots 26 and 27 formed in the end faces of the members 21 and 22.

A screw 28 is utilized to secure the key 24 in its key slot and is countersunk therein. A spring 29 surrounds the cylindrical portion 23 of the spindle and abuts against the opposing faces of the conical journal members to continuously urge them apart and into bearing relation with the conical bearing members 18 and 20. It is to be noted that the conical journal members have lubricant receiving pockets 30 formed in the periphery thereof, and there may be a number of these pockets spaced circumferentially about the periphery of the members. It will also be noted from the construction that an enclosed space 31 is thus formed between the opposing faces of the conical members and surrounding the spindle. This space is connected by a conduit or passage 32 to a supply pipe 33 through which a lubricant under pressure is delivered to the space 31, and the pressure of this lubricant in the space acting against the opposing faces of the conical journal members continuously urges them into engagement with the conical bearing members 18 and 20.

The pressure lubrication also enters the pockets which are discontinuous and thereby during rotation of the journal members, a hydro-dynamic iilm is created in the clearance space between the opposing faces of each pair of conical members. It is well known in the art that such a hydro-dynamic film will generate its own pressure, the value of which will depend upon the speed of rotation of the relatively movable parts. Since, as recited supra, the spindle is rotated at a speed during the truing operation which is eight or ten times its regular operating speed, the pressure of the hydro-dynamic film will be very much greater at the higher speeds, and, therefore, since this pressure is created within the clearance space between the surfaces of the relatively rotating members, an axial component will be created to urge the conical journal members toward one another and thereby increase the clearance between the conical members, and thus make a freer running bearing; while at the grinding speed the hydro-dynamic pressure will be very much less, and the lubricant pressure in the space 31 will urge the conical parts into a tighter it and thus better resist lateral thrust on the spindle caused by pressing against the work.

It will be noted from the construction, so far, that nothing has been described which prevents axial movement of the cylindrical portion 23 through the bearing and in order to take up the axial thrust on the spindle during the grinding operation, a separate axial thrust bearing, indicated generally by the reference numeral 34, has been provided at the end of the spindle. This bearing is contained within a thimble housing 35 threaded at 36 in a flanged sleeve 37 fitted in a bore 38 of the housing 1t). This thrust bearing is of any commercial type, and its particular construction forms no part of the present invention. The shaft may also be supported and steadied at this end by a conventional radial thrust bearing 39 mounted in the bore 38.

t will thus be seen that in this construction the spindle is located axially by the thrust bearing 34 which thereby absorbs the axial thrust on the spindle, and that the tapered conical bearings automatically adjust themselves to automatically maintain the proper running clearance within the bearing in accordance with its speed of rotation. The spring 29 holds the conical members in engagement when no hydraulic pressure exists in the charnber 31 as when the machine is shut down, and it is also to be noted that if any wear occurs between the opposed bearing surfaces that such wear will be automatically taken up.

In Figure 2, a modified form of the construction shown in Figure l, is illustrated in which the radial and axial thrust are taken in one bearing. In this construction the spindle housing 40 is provided with a first bore 41, in which is fixed the conical bearing member 41 held against rotation by the lock screw 42 and positioned by the liange 43 engaging the shoulder 44 formed by the larger bore 45. The second conical bearing member 46 is mounted in the bore and located by its flange 47 against the end of the housing and secured in position by the cap plate 43 fastened to the housing by suitable screws 49.

The regulating wheel spindle 50 has a first conical journal member 51 mounted thereon but secured to the spindle for rotation therewith. It is held against axial movement with respect to the spindle by means of a ring 52 fitting in an annular groove 53 and abutting one end of the conical member 51, while the other end 54 abuts the end of a ring 55 surrounding the spindle 50 and secured to it by a screw 56. This screw also passes through a key 57 fitted in a key slot 58 formed in the spindle 51, and the end 59 of the key engages a key slot 60 formed in the end of the member 51, as shown in Figure 3, to insure that the member 51 rotates with the spindle.

A second conical member 61 is slidably mounted on the cylindrical portion 62 of the spindle into engagement with the conical member 41 and is held in engagement therewith by a series of springs 63 mounted in the collar 55 and thereby interposed between the collar and the member 61. The member 61 has a key slot 64 cut in the face thereof as shown in Figure 3 and thereby in keyed relationship to the key 58 for rotation with the shaft but still capable of axial movement relative to the shaft.

By introducing lubricant pressure through the channel 65 into the space 66 the conical journal member 61 is maintained in engagement with the conical member 41 but due to the fact that the other conical journal member 51 is secured with the spindle, the hydraulic pressure will act against the end of the member 51 to maintain it in engagement with its opposed conical bearing member 46 and `also shift the shaft or spindle axially and thereby act as a thrust bearing to prevent axial movement of the shaft. Since the conical bearing now provides against axial, as well `as radial thrust on the spindle, the other end of the spindle, such as the cylindrical portion 67, may be journaled in a plain bearing, such as the inner sleeve 68, and the outer sleeve 69 fitted in the bore 70 of the housing 40.

There has thus been disclosed an improved bearing construction for the purposes disclosed which automatically adjust the running clearance in the bearing in accordance with speed, and thereby makes possible better centralization of the spindle in its bearing under all operating conditions.

What is claimed is:

1. In a bearing structure, a fixed support having a bore formed therein, said bore having axially spaced conical bearing surfaces in the opposite ends thereof, a shaft mounted in said bore having spaced conical journal members mounted thereon interfitting said bearing surfaces, said journal members being splined to the shaft for relative axial movement with respect to the shaft and each other, and means to introduce lubricant into said bore under pressure to urge said journal members into engagement with said conical bearing surfaces to automatically take up wear and to lubricate the interfitting surfaces of said members.

2. In a bearing structure, a fixed support having a bore formed therein, said bore having axially spaced conical bearing surfaces in the opposite ends thereof, a shaft extending into said bore having spaced conical journal members mounted thereon within said bore and interfitting said bearing surfaces to close the ends of said bore, said journal members also being splined to said shaft for relative axial movement of the shaft, spring means surrounding the shaft and engaging adjacent ends of said journal members for urging them into engagement with said conical bearing surfaces to support the shaft against lateral movement during non-rotation thereof, and means for introducing lubricant under pressure into the bore to apply end pressure to said journal members for providing an additional urge on said journal members during rotation of the shaft.

3. In a bearing structure, a fixed support having a bore formed therein, said bore having axially spaced conical bearing surfaces, a shaft mounted in said bore having spaced conical journal members mounted thereon, said journal members being splined to the shaft for relative axial movement, means for introducing lubricant under pressure to the space between said journal members to urge them into engagement with said conical bearing surfaces, lubricant receiving pockets formed in said journal members to develop a hydrostatic pressure between said conical surfaces during rotation of the shaft whereby the degree of said pressure will control the running clearance between opposed conical surfaces.

4. In a bearing structure, a fixed support having a bore formed therein, said bore having members mounted in opposite ends in which are formed conical bearing surfaces, a shaft in said bore having spaced conical journal members mounted thereon intermediate said tiret-named members and in operative engagement with the bearing surfaces'thereof forming a closed chamber within said bore, said journal members having spline connections to the shaft permitting axial movement of said members relative to the shaft and for rotation by the shaft, spring means mounted in said chamber between said journal members for urging them into intertting engagement with said conical bearing surfaces to support said shaft in a central position under static conditions, and means to introduce lubrication under pressure to said chamber during rotation of said shaft.

5. In a bearing structure, a xed support having a bore formed therein, a pair of bearing members mounted in opposite ends of said bore and having internal conical bearing surfaces, means to fix said bearing members in said support against axial and rotatable movement, a spindle in said bore having spaced conical journal members thereon between said bearing members and interfitting with said bearing surfaces to form a closed chamber within said bore, means to spline said journal members on said shaft for rotation thereby relative to said bearing members and for free axial movement relative to said shaft, a rst pressure means interposed between said journal members in operative engagement with adjacent ends thereof to centrally support said shaft under static conditions and take up wear automatically during rotation thereof, and means to introduce pressure lubricant to said chamber during rotation of said shaft to lubricate said bearing surfaces.

References Cited in the le of this patent UNITED STATES PATENTS 319,650 Whitney June 9, 1885 1,692,008 Van Brunt Nov. 20, 1928 2,253,110 Cornell, Jr. Aug. 19, 1941 FOREIGN PATENTS 88,577 Austria Sept. 15, 1921

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