US2171208A

US2171208A - High speed spindle construction

Info

Publication number: US2171208A
Application number: US149854A
Authority: US
Inventors: Albert H Dall; Frederick S Haas
Original assignee: Cincinnati Grinders Inc
Current assignee: Cincinnati Grinders Inc
Priority date: 1937-06-23
Filing date: 1937-06-23
Publication date: 1939-08-29
Anticipated expiration: 1956-08-29

Description

2 sheets-Sheet 1 A. H. DALL ET AL HIGH SPEED SPINDLE CONSTRUCTION Filed June 23, 1937 fam/mai //m l1 ATTORNEY.

Aug. 29, 1939.

A. H. DALL ET A| 2,171,208

HIGH SPEED SPINDLE CONSTRUCTION Filed June 23, 1937 2 Sheets-Sheet 2 Aug. 29, 1939.

I I I fd l I I ,I

I ATTORNEY;

flange portion I6 on one end, is insertedl in.

Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE ,man SPEED sPmDLE coNs'rmJcTIoN Albert n. m11, silerton, and Frederick s. Haas, Cincinnati, Ohio, assignors to Cincinnati Grinders Incorporated, Cincinnati, Ohio, a

corporation of Ohio Application June 23, 1937, Serial No. 149,854

5 Claims.

This invention relates to machine tools and more particularly to an improved form of high speed spindle construction for the rotary tools thereof.

One of the objects of this invention is to provide means for supporting a machine tool spindle for high speed rotation.

Another object of this invention is to provide improved means lfor anti-frictionally supporting a spindle for high spe'ed rotation and at the same time maintaining the plane of rotation of the cutting tool, such as a grinding wheel, in a predetermined plane Within precision limits.

Other objects and advantages of the present invention should be readily apparent by reference.to the following specification considered in.

conjunction with the accompanying drawings illustrative of one embodiment thereof, but it will be understood that any modifications may be made in the specific structural details within the scope of theappended claims without departing from or exceeding the spirit of the invention.v

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

'Figure 1 is a sectional view of a high speed spindle construction embodying the principles of this invention.

Figure 2 is a Section on the line 2-2 of Figure 1.

Figure 3 is a section on the ure 1. v IFigure 4 is a sectional view showing a, modied form of the invention.

line 3-3 of Fig- Figure 5 is a detail view of one lof the 'double I tapered rocker shoes shown in Figure 4.

Figure 6 is an end view of the s hoe shown in Figure 5.

Figure 7 is a schematic diagram showing the relationship vof the angles of the double tapered shoe with respect to the axis of the spindle.

Figure 8 is an enlarged detail of one of the shoes shown in-Figure 4. Figure 9 is a detail view showing the details of the .thrust bearing shown in Figure 1.

In Figure 1 of the drawings, the reference numeral IIJ indicates a part of the structure of a. machine too'l, such as a grinding machine, said structure comprising spaced walls II and I2 having aligned openings I3 and I4 respectively formed therein. A sleeve I5, having a these openings with the flange I6 abutting one side ofthe wal1 .I2, and held in place by a nut l1 threaded on vthe end of the sleeve and engaging the outside 0f the wall II. The sleeve rests on the bottom of the openings I3 and I4 and is held against rotation by a plurality of dowel pins I8 and I9, and is prevented from lifting by means of set screws 20 and 2|.

The sleeve I5 has aligned bores 22 and 23 formed in opposite ends thereof and a tool spindle 24, which is disposed in the sleeve, has reduced journals 25 and 26 passingthrough these aligned bores.

One end of the spindle 24 has a shoulder 21, against which an annular guard 28 is adapted to be positioned. A grinding wheel 29 is positioned on the spindle with one side in engagement with the central boss 30 of the guard 28 and held against rotation by a clamping screw 3| which engages an enlarged flange 32 mounted on the other side of the grinding wheel, said screw being threaded in an axial bore in the end of the spindle.

The grinding wheel may be provided with a trued surface 33 of precision width which is adapted to fit into and engage a recess 34 in a work piece 35 for finishing the bottom surface of said recess. Since the grinding wheel'is small, it must be rotated at a high rate for obtaining the desired surface speed.

In order to obtain the necessary speed of rotation with a minimum amount of power, a form of anti-friction bearing means is provided for supporting the spindle at spaced points which will permit of high speeds of rotation. A plurality of rocker shoe bearing members 36 are provided in the bore 23 of the sleeve I5 for engagement with the journal 26 of the spindle. Each of these rocker shoe members is provided With a boss 31 on the outside periphery, as shown in Figure 8, the radius of the curvature of which is less than the radius of the bore 23 whereby only line contact Ais made between the shoe and the bore, so that the shoe is free to pivot a lim- 'ited amount. A set screw 38 is provided for holding the shoe in position circumferentially and at the same time permitting the pivoted movement. The bearing surface 39 of the. shoe has a beveled endlso that rotation of the shaft in its prescribed'direction lwill cause oil to be' drawnv in between the shoe and the journal and cause a hydrostatic pressure to be generated by the hydrodynamical condition in the oil film. The variations in the pressure of the fluid will cause the shoe, to rock avery limited amount about its pivot by line contact with the spindle The thickness of the shoe and Oil lm cetermines the position of the axis of the shaft with 55 .off a suiiicient amount to permit free rotation of the spindle.

A similar set of bearing shoes is provided in the bore 22 and by the same method of set up, it will be apparent that it is possible to align the axis of the spindle parallel to the axis of bores 22 and 23.

To obtain the best results these bearings I should be supplied with lubricating oil under some pressure, and to this end the sleeve i5 is provided with openings 4I through which oil may be introducedfto the interior of the sleeve from a suitably located reservoir or from a pump. In order that a pressure may be built up within the sleeve, oil seals are provided at each end of the sleeve and to accommodate these, each endl of the sleeve is counterbored as at d2 and d3 to form shoulders against which the sealing members dll and Ll5 may bear. These members have a running t with the shaft and are held against the shoulders by springs 56, which are held in position by cup shaped members -dll, threaded into the counterbores. Since there is very little leakage past these seals, it will be apparent that a substantial pressure may be built up within the sleevev to' maintain the desired supply of lubricant to all of the bearing shoes so that the necessary hydrostatic pressure will be generated `for supporting the spindle.

The spindle 24 is provided with a tapered portion 68 upon which is keyed a driving pulley 49. A belt 50 may be passed around this pulley for actuating the same.

It will be noted that since the rocker shoe bearing surface extends parallel to the surface of the spindle, it is free to move axially, which would make the position of the grinding wheel 33 with respect to the Work uncertain, and therefore means have been provided for stabilizing the axial position of the spindle. One form that this means may take is shown in Figures 1 and 9, and comprises a thrust bearing 5I consisting of an inner race member 52 which is xed with the spindle and an outer race member 53 which isv held in a. fixed`position in the housing 515. A lubricant reservoir 55 may be attached to the housing 54 and' connected by a channel 56 for lubrication of the thrust bearing.

If so desired, the thrust bearing shown in Fig- The spindle 2d is provided with double tapered journals 6| and 62 and it will be noted from Figure '7 that a line of contact between the tapered journal and the spindle, and lying in a radial plane, such as the line 63wi1l make an acute angle 6d with the axis of the spindle. The shoes 51 are provided with hardened inserts 65 having conical recesses 55 for receiving the end of locking screws-Gl.

There are three shoes 51 equally spaced about the periphery of the double cone journals on the spindle andthe method of set up is the same as that previously described in connection with the plane rocker shoes. It will now be apparent that the double cone rocker shoes are capable of preventing axial movement of the spindle in either direction by generating an hydrostatic pressure which acts perpendicular'to the double cone journals, and therefore at opposite acute angles to the axis of the shaft resulting in opposed axial components which prevent axial oscillation of the spindle.

We claim:

1. In precision high speed spindle construction, the combination with a spindle having spaced bearing portions formed thereon, of a support therefor having bearing recesses alignable with the bearing portions on the spindle, a plurality of circumferentially spaced bearing shoes circumscribing the spindle Within each of said recesses, said shoes having inner portions corresponding in shape to the bearing portion of the spindle engageable thereby and outer faces supportable for oscillation relative to the circumscribing wall of the bearing receiving recesses, means maintaining said shoes against axial displacement in the recesses, means coupled with said recesses for maintaining the same filled.l

with lubricant under appreciable hydrostatic pressure whereby upon rotation of the spindle wedge-like oil lms will be produced intermediate the shoes and bearing portions of the spindle, maintaining the spindle in fixed axial position under varying load conditions, certain of said shoes -having inner faces reacting in a,l direct radial direction against the bearing portions of the spindle for retaining the same against ra dial movement and other of said shoes, each having individual angularly related, portions creating forcecomponents reacting against the spindle in opposite balanced angular directions in a radial plane whereby to restrain the spindle against longitudinal movement as well as radial 'displacement of its axis of rotation.

2. In precision high speed spindle construction, @the combination with a spindle adapted to be rotated at high speed, of means for supporting the spindle including a supporting element providing closed bearing receiving chambers, groups of bearing. elements disposed along the chambers .in circumscribing relation to the spindle, said elements'being mounted Afor limited oscillatory movement with respect to the spindle whereby to create wedge-like oil films during rotationof" the spindle, restraining the spindle against radial displacement, certain of said elements having portions disposed in non-parallel relation with respect to the axis of the spindle, the spindle having corresponding, non-parallel zones ofgeneral frustro-conical type opposing the faces of said bearing members, and means for maintaining the entire series of bearing elements submerged in lubricating medium under hydrostatic pressure whereby the wedge-like films created on rotation the combination with a housing member having' spaced bearing receiving recesses of la spindle extending transversely of the housing and into said p an oscillatable non-translatable outer connection with the housing and having their respective inner faces shaped to conform to the adjacent included bearing portion of the spindle, and means for maintaining the housing and bearing chambers lled with lubricant under appreciable hydrostatic pressure whereby on rotation of the spindle interposed wedge-like lms will be created between the respective bearing members and the spindle, steadying the same at spaced points against radial displacement of the axis of rotation thereof under varying load conditions and simultaneously reacting on the tapered zones thereof to prevent longitudinal displacement of the spindle.

4. 'I'he combination with a rotary spindle having opposed tapered zones providing frustro-conical bearing portions, of a precision mount therefor including a support having a recess adapted to circumscribe the zones in spaced relation thereto,`bearing members interposed between the support and spindle disposed in a. series circumscribing the bearing portion of the spindle, each of said bearing members having oppositely inclined tapered segmental recesses formed in the inner faces thereof in conforming relation to the zones on the spindle, means mounting said members for oscillatory, non-translatory movement with respect to the support and means for maintaining said bearing portion of the spindle and circumscribing shoes submerged in lubricant under appreciable hydrostatic pressure whereby a continuous cil film of homogeneous character is produced between all of said bearing members and the bearing portions of the spindle restraining the latter against radial and translatory displacement under varying loaded conditions.

5. A bearing structure of the character described for prevention of radial and longitudinal displacements of a precision spindle under varying load conditions, including a spindle having opposed spaced frustro-conical bearing portions, and a plurality of bearing shoes arranged in circumscribing relation with respect to said portion of the spindle, a supporting member providing a chamber circumscribing said spindle portion and shoes, means mounting said shoes for individual loscliation in 'a plane transversely of the axis of the spindle, each of said shoes having spaced frustro-conical segments on its inner face substantially conforming .to the shape of the spindle for interfitting engagement therewith, the spacing of said portions providing an intervening lubricant receiving groove, and means maintaining the bearing receiving chamber completely filled with lubricant under hydrostatic pressure whereby on rotation of the spindle wedge-like.

lms will be produced between the bearing member andspindle reacting on the spindle in a di-v rection at an angle to the axis thereof whereby jointly to vrestrain the same against both radial and longitudinal displacements under varying loads.

ALBERT H. DALL. FREDERICK S. HAAS.