US2629975A

US2629975A - Abrading machine

Info

Publication number: US2629975A
Application number: US169742A
Authority: US
Inventors: Desenberg Josef
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-06-22
Filing date: 1950-06-22
Publication date: 1953-03-03
Anticipated expiration: 1970-03-03

Description

March 3, 1953 J. DESENBERG 2,629,975

ABRADING MACHINE Filed June 22, 1950 4 Sheets-Sheet l rn-I7' ATTORNEY March 3, 1953 J. DESENBERG 2,529,975

ABRADING MACHINE Filed June 22, 195o 4 Sheets-Sheet 2 i llllll- A oRNEY March 3, 1953 Filed June 22, 1950 J. DESENBERG ABRADING MACHINE 4 Sheets-Sheet 3 ew J S Iza/ 'BZ lI INDVEN''OR b eden er 23% 906e;

March 3, 1953 J', DESENBERG 2,629,975

ABRADING MACHINE Filed June 22, 1950 4 Sheets-Sheet '4 IIS 3G 20 Il@ :Ligia /IIB H9 Scoef :Dec nbefg (jh-romay Patented Mar. 3, i953 UNITED STATES PATENT CFFICE.

ABRADING MACHINE Josefv Desenberg, Rockford, Ill'.

ApplicationJiune 22, 1950;.Serial No. 169,742

1I Claims. l

This; invention relates to an abradingmachine; whichV is; adapted to generate'/ a. flat or; curvedr surface on a,l workpiece such as a lens and in whichthe; work andl an abrading or grinding element rotate about axes lying: in a. common plane4 and intersecting at the center of curvature of the surface being generated with thev axis of rotation of the; Work, intersecting the area. or zone; ofl engagement between the workl and the abradY ing. element. My'V priory Patent No. 2,352,146 shows aY machine of the. a-boveY character over 4which the present invention is an improvement.

One object oithe invention is toy provide a, machine of the above character in which. thev abrading element is supported ina novel manner on. opposite,r sides of the. com-monplane of the'. axes of the work and the:v abrading elernent so. as. to provide, a rugged and stable mountingwhich. maybe.,y adjusted easily and accurately for concave.v aswell as convex: work surfaces.

VAnother object is to perform. both rough and finish grinding operations` on a workpiece in successive; steps in.4 a-y single machine without stopping the machine: or readjusting the same` A" more; detailed object-is tf1/effect the foregoing, object by mounting a plurality of rough and-` iinish grinding; tools` for rotation` along a corn-*- mon circular path about. aeommon axis with portions, of the tools alternatingeach other along the .pa-th; and;v movable. selectively into. engagement.. with thework.

A1 further obiect. is. to. provide, a. machine of the aboveV character in which truing ofthe abradf-l ing element, is, effected during a lens grinding operation by a truing; element mounted concentrically with respect to. the lens; so as to.. simplify the machine. andy facilitate accurate adjustment. thereof.

Qther objects; and advantages of the invention willi become apparent,` from. the following detailed description taken` in connection with the, accompanying drawings, in whichk Figurer l is a. fragmentary sectional view of, a machine embodying the novel features ofthe present. invention taken along the line. l.-l of Fig. 2.

Fig. 2 is a fragmentary sectional view taken along the line- 2-2 of Fig. l.

Fig. 3 is an enlarged sectional View taken along. the line. 3--31of Fig. 4.,

lFigure 4. is a plan view of,v one form of. thev grinding elements.

Figs. 5,. and 6 are views similar to Figs. 3 and 4" and showingV a modified. formv of the grinding elements, Fig. being a section taken along the line'iiL--i` of'Fis. 6;

Figs. 7 and, are viewssimilar to Figs. 3. and 4' showing another modification, Fig. 7,' being aseo.- tion taken along the line [-Tof Fig. 8`.

Fig. 9 is a sectional/view taken along the linev 9-9 of Fig.. 10.

Fig. 10 is a sectional view taken along the linek llll0 of Fig. 1.

Fig. 11 is a fragmentary view similar to Fig. 4 showing still. another modificationv of the grinding elements.

Fig. 121is, an enlarged view showinga modification of themachine shown in Fig. 1'.

Fig. 13 is a fragmentary sectional view showing the. relation of, the parts, of the machine shown in Fig. 12 with a convex lens.

Fig. 14 is a schematic. plan view of. the. parts shown. in Fig. It".A

Fig. l5 i's a view similar to Fig; 13l showing.A the: relation of the parts with a4 concave lens.

Fig'. 16 is a schematic plan view of the parts shown in Fig. 15.

While the invention is susceptible of various modifications and alternative constructions, it is' shown in the drawings and described inthe speci"- cation in a machine especially adapted fc'irhigh` precision and' highv production grinding ofV lenses. It. is to be understood, however, that I do notA intend to' limit thel invention by such disclosure but aim to cover allmodications and-` alternative` constructions falling within. the spirit and scope of the invention as expressedin the appended' claims. Grinding" as used ink the; specification and claims contemplates abrading of any degreel of finenessincluding polishing.

In the improved: machine-shown in, Figs. I and 2, a lens blank 20 is mounted in a holder 2|A and1` isF ground by the action of a tooly 22 mounted in another holderV 2.31 The tool holder 23 is xed on' aV spindle 24: and the work' holder 2l on a; second spindle 25, the Worky being held onl its holder by suction derivedI from a pump (not shown) which communicates with a passage 26v extending axially through the second spindle'. Herein, all'of the movable parts of themachine are mounted' on a frame comprising` generallyv a base (not shown) adaptedA to` rest on; a supporting surface and having parallel upstanding side walls 21' connected by parallel front and rear' walls 28 and 29 with an uprightv columnv llprojecting rearwardly fromthe intermediateportion" ofthe rear wall.

The tool' and worlrl spindles 24 and 25- are mounted on the frame for rotation about axes 33 and? 3'4 whichliein a common plane 3| (Fig. 1)! and intersect each other at the center 35.A 02Ev curvature;V (Figs. I3A and;V 15) of; the. lensy surface 36 being ground with the work axis 34 passing through the Zone of engagement between the lens 20 and the tool. To adapt the machine for grinding both concave and convex lens surfaces of widely varying radii of curvature, the spindles are mounted for selective pivotal adjustment of one of the spindles about an axis 32 (Fig. 1) normal to the plane and also for bodily adjustment of one of the spindles in the plane in a direction normal to the pivotal axis. Thus. when the work surface 36 is convex as shown in Figs. 1, 2, 12, and 13, the spindle axes intersect on one side of the work surface, herein below. where the center 35 of curvature is located. However, when the work surface is concave (Fig. 15), the intersection of the axes at the center of curvature is on the other side or above the work surface.

The present invention contemplates the provision of an extremely rugged and accurate mounting for at least one of the spindles 24 and 25 while still permitting the pivotal and bodily adjustments of the spindles above referred to. This is accomplished by supporting the spindle-s at widely spaced points located on opposite sides of the plane 3l so as to reduce substantially any deflection of the spindle axes 33 and 34 resulting from a deflection of the spindle supports. Such support of the spindles makes it possible to achieve a very high degree of accuracy in the precision grinding of lenses. Preferably, though not necessarily, both the pivotal and bodily adjustments are effected by moving only the tool spindle 24, the axis of the Work spindle 25 being fixed.

In this instance, the common plane 3l of the

axes

33 and 34 is disposed between and parallel to the frame side walls 21 and the mounting for the work spindle 24 includes widely spaced adjustable supports 38 located on opposite sides of the plane and at opposite ends of an elongated crosspiece 39 which is secured to and extends transversely across an elongated hollow upright member 49. The latter lies in the plane of the axes and carries a sleeve 4l having bearings 42 at opposite ends to rotatably support the tool spindle 24. The shaft 43 of an electric motor 44 secured to and movable with the hollow member is connected through a belt 45 to a pulley 46 fast on the upper end of the tool spindle for rotating the latter. Herein, the crosspiece 39 is U-shaped and formed integral with the hollow member 40 so that the two form a bifurcated yoke having legs 41 at its lower end disposed generally parallel to the member at widely spaced points on opposite sides of the plane.

The swinging adjustment of the tool spindle 24 above referred to is effected by pivotally connecting the yoke legs 41 and the supports 39 which herein are in the form of parallel upright arms lying along the yoke legs on the outer sides of the latter. To pivotally connect the yoke legs and the arms, trunnions 48 having heads 49 clamped to the yoke legs as by screws 59, project outwardly from the legs in a direction normal to the plane of the axes and are journaled in the support arms 38. Nuts 5l acting against washers 52 on the trunnions are threaded on the outer ends of the latter to secure the yoke against movement along the trunnion axis. If desired, the Washers may be keyed to the trunnions and formed with a scale to indicate the angular position of the tool spindle 24 about the trunnion axis 32.

. Disposed on opposite sides of the hollow member 49 and extending transversely of the trunnion axis are elongated parallel shafts 53 which, adjacent one of their ends, are journaled in and secured against axial movement relative to bearing blocks 54 pivoted on the hollow member 40 adjacent the upper end of the latter. At their other ends, the shafts are threaded into a shaft 55 disposed parallel to and rearwardly of the trunnion axis 32 and journaled intermediate its ends in the upright column 30. By turning handwheels 56 secured to the parallel shafts, the upper ends of the hollow member and the tool spindle are swung about the trunnion axis 32 in the plane 3i of the axes of the tool and the work. Preferably, to enable the shafts to be turned in unison and thereby facilitate accurate adjustment of the tool spindle, a chain 51 is stretched taut between sprockets 58 fast on the shafts.

The bodily adjustment of the tool spindle 24 in a plane of the axes of the latter and the work spindle 25 is effected in the present instance by two parallel screws 60 which extend along the frame side walls 21 parallel to the latter and are journaled at opposite ends in the front and intermediate frame walls 28 and 29. The lower ends of the yoke supporting arms 38 are threaded onto the screws while the upper ends of the arms slidably receive and are guided by rods 6I disposed parallel to the frame side walls 21 and secured at opposite ends to the front and intermediate walls. By turning handwheels 62 fast on the front ends of the screws, the supporting arms 36 are adjusted along the screws and the tool spindle 24 is thereby adjusted bodily in the plane 3l in a direction normal to the work axis 34. Preferably, the screws 6l) are connected as by a chain 63 stretched taut between sprockets 64 on the rear ends of the screws so that the supporting arms 38 may be adjusted simultaneously along the respective screws.

To simplify the grinding operations performed on each workpiece 20 and adapt the machine for high production grinding operations, the invention contemplates the provision of a second grinding tool 65 (see Figs. 1 and 3 through 8) which is of a different coarseness than the tool 22 above described and is arranged in a novel manner with respect to the latter so that the tools may be brought selectively into engagement with a common zone of the workpiece including the center of the work surface 36 without stopping the machine or changing the settings of the work and tool axes 33 and 34. For this purpose, the

tools

22 and 65 are both mounted for rotation about the tool axis 33 with a portion of each tool spaced angularly from the other tool around a circular path concentric with the tool axis and with each tool movable selectively along the tool axis and into engagement with the work. Preferably, each tool comprises a plurality of angularly spaced arcuate abrading elements which intervene between the spaced elements of the other tool.

Such an arrangement of the

tools

22 and 65 is shown in Figs. 1, 3, and 4 in which the tool spindle 24 is made hollow to receive an inner spindle 66 splined as at 61 (Fig. 1) to the hollow spindle so as to rotate therewith but to move axially relative thereto and having an inner tool holder 68 secured to its inner end. The arcuate abrading elements 69 of the tool 22 on the hollow spindle are coarser than the elements 10 of the second tool 65 and are secured to the outer ends of angularly spaced projections 1| which extend along the tool axis 33 and form a partof the outer holder 23. The arcuate elements of the second tool 65 are secured to the outer ends of similar projections 12 forming a part of the inner tool holder and intervening between the outer holder projections 7| which are longer than the inner projections 'l2 so that, with the inner spindle retracted, only the rough grinding elements 69 engage the surface 30 being ground.

While the inner spindle may be moved in vari-4 ous ways to project the finish grinding elements I0 axially beyond the rough elements 69 and into engagement with the work, this is effected hydraulically in the present instanceby two servos M (Figs. 1 and 2) each including anv air cylinder 'l5 mounted on a plate 16 secured to the upper end` of the sleeve 2| in the hollow member 40 of the yoke. Slidable in each cylinder is a piston Tl whose rod is connected to a cross bar I8 secured to the outer end of the inner tool spindle 56.

To facilitate rap-id loading and unloading of lenses from the work holder 2|, the work spindle 25 which in this instance rotates about a fixed vertical axis is mounted on a vertically slidable carriage i3. The latter includes an upright hollow body surrounding a sleeve 80 having bearings 8| therein rotatably receiving the work spindle with the work holder secured to the top of the sp-indle. Projecting outwardly in opposite directions from the top and bottom of the hollow body are horizontal arms 82l carrying bearings 83 which slide along vertical guides 84 secured at opposite ends to vertically spaced horizontal flanges 85 projecting inwardly from the frame side walls 2. Secured to and movable with the carriage is an electric motor 80 whose shaft 8'! is connected by a belt S8 to a pulley B9 keyed to the lower end of the work spindle 25 for rotating the latter. If desired, the lens and the tools 22 and 55 may be enclosed during wet grinding operations in a casing comprising two

telescoping parts

90 and 0| respectively secured to the yoke and to the sleeve 80.

In this instance, the carriage 19 is yieldably urged upwardly into a grinding position by weights 92 secured to chains 93V extending around rotatable pulleys 90 on the side and rear frame walls 2l and 29 and connected to the motor 86 and studs 95 projecting outwardly from the lower carriage arms 82. Upward movement of the car-` riage is limited by the engagement of one of the lower carriage arms with an enlarged upper end 36 of a vertical rod 3l slidable in the arm and threaded at its lower end in one of the lower ilanges85.

While retraction of the work carriage 'I9y downwardly may be effected manually, i-t is preferred to use a hydraulic servo 93 (Figs. 1 and 2) having a cylinder 99 secured to one of the frame flangesv 85 and having a piston |00 therein. The rod |0| of the piston extends through the adjacent lower carriage arm 82 and at its outer end is enlarged to engage the arm and pull the carriage.

downwardly when the servo is energized.

In operation, let it be assumed that a lens:

44 and 86 are energized to rotate the work andl the tool spindles 24, 25, and- |50y and the'servof.

98 is deenergized to lpermit feeding of the l'ens' blank 20 under the action of the weights 92 into engagement with the rough grinding elements` 69. The lens continues to feed into the rough grinding elements until the carriage engages. the stop 96 and the roughgrinding elements are nol longer effectual to grind the lens, an ac*-l tion corresponding to sparking out in metal grinding operations. At this time, air is ad-V mitted to the rod endsv of the cylindersi`|5 to. adV vancethe nish grinding elements 10 under light air pressure axially beyond the rough elements 69 and into engagement with the work. Since the rough and finish grinding elements are dis-Y posed along a circle concentric with the tool axisl 33, the nish elements engage a zone'of'the lens surface traversed by the rough elements. After a short time determined from experience and` depending on the type. ofv lens being ground, air is admitted tothe head ends of the cylinders '|51 to retract the finish elements and the carriage servo 08 is energized to retract the carriagefor removal of the finished lens and the insertiony of another lens blank.

The angularly spaced rough andnish grinding elements may take various forms. One modication is shown in Figs. 'I and 8 in which each of the elements |02 and |03 are continuous so as to form an annulus with projections and notches on the inner periphery of' the outer orv rough element |02r alternating with each other and mating with complementary projections and notches on the outer periphery of the inner or finish element |03.

Another modied form is shown in Figs. 5 and 6 in which three sets of grinding elements, a`

In the modification shown in Fig. l1, rough elements H0 and finish elements are formed as circular blocks of abrading material which arey embedded in angularly spaced portions of. two tool holders ||2 andAv H3; These portions are arcuate in cross sectionand movable axiallyrelative to each other inA a manner similar toV the

holders

23 and 68 above referred to.

The machine described above may, merely byJ the substitution of a few parts, be used for performingv very ne grinding` or polishing operations in which it is desirable to effect a truingA operation on the polishing tool during the polishing operation. Such a` modified machine, is shown in Figs. 12 through 16 in which parts corresponding to the parts above described are indicated with corresponding reference numbers. The simultaneous polishing and truing operations are effected by rotating a polishing tool H5, a truing element H6, and the lens blank 20 about axes which intersect at they center 35 of curvature. of the surface 36 beingy groundand' feeding the polishing tool axially into engagement with the truing element: and the. lens' blank axially into engagement with. the. polish.- ing tool. In the form shown in Figs. 12,13, and 14, thev polishing tool ||5` is concave and the, work surface ,is convex' whereas, the: form 7 shown in Figs. 15, and 16, a convex polishing tool is arranged to engage a concave lens surface.

To simplify the construction of a polishing machine of the above character and to facilitate accurate positioning of the truing element ||6, the polishing tool IIS, and the lens 20 for precision nishing of the latter, the invention contemplates mounting the truing element concentrically with respect to the lens so that the axes of the truing element and the work coincide. Thus, all three axes of the tool, the truing element, and the Work may be brought into the proper relation of intersection at the center 35 of curvature of the work surface 38 merely by adjusting the positions of the tool and the work axes 33 and 34. In the present instance, the truing element I6 is mounted in a holder ||1 on a vertical hollow spindle spindle I |8 journaled in the work carriage 19. The work holder 2| is concentric with the truing element holder and is secured to the inner end of an inner work spindle ||9 journaled in and movable axially relative to the hollow spindle ||8. The motor 86 (not shown in Fig. 12) mounted on the carriage 19 rotates the hollow spindle |I8 through a belt (not shown in Fig. l2) and a pulley |26 keyed to the outer end of the spindle and secured thereon as by nuts. At the same time, the motor rotates the inner spindle independently of the truing element and at a different speed through another belt (not shown) and another pulley |2| keyed to the inner spindle.

To feed the lens 20 axially of the truing element, the inner work spindle I I9 is secured to a slide |22 (Fig. l2) which is mounted on the vertical guides 84 and is movable relative to the carriage 19 along the guides. The slide is yieldably urged upwardly by weights (not shown) acting through cables |23 connected to the slide. Similar cables |24 connect the carriage studs 95 and the weights 92 (not shown in Fig` l2) to urge the carriage upwardly. Upward movement of the carriage is limited in this instance by two individually adjustable stops |25 which are rigid with brackets |21 secured to the guides 84 and are located at widely spaced points on opposite sides of the plane 3| to engage the outer ends of the upper carriage arms 82. By using two stops which are adjustable individually and engage the carriage 1S at widely spaced points, it is possible to locate the work axis 34 precisely in the plane 3| and thereby secure accurate positioning of the lens 20 regardless of` any deflection in the parts caused by temperature changes. Shock absorbing devices |26 of suitable construction may be mounted on the upper carriage arms to engage the brackets |21 and reduce the rate of upward movement of the upper carriage arms 82 just before engagement of the latter with the stops.

Herein, the polishing tool I is secured to the inner tool spindle 68 which is fed axially toward the truing element IIB by a reversible electric motor |28. The latter is mounted on a plate |29 secured to the outer end of the inner spindle and acts through a screw |36 to turn worm wheels |3| which are journaled in the plate and are threaded on parallel rods |32 secured as by bolts to the plate 16 at the upper end of the sleeve 4| in the hollow member 40 of the yoke. When the motor is energized, the spindle plate |29 is moved toward or away from the sleeve plate 16 and the polishing tool is moved inwardly or outwardly along its axis depending on the direction of rotation of the motor.

In the operation of the polishing machine, the yoke and the stops |25 are adjusted so that the axis 33 of the polishing tool ||5 will intersect the axis 34 of the truing element I|6 and the work 20 at the point which coincides with the center 35 of curvature of the work surface and is the center of curvature of the truing surface of the truing element (see Figs. 13 and 14) at the time that the carriage arms 82 are engaging the stops. Then, the carrage is retracted by energizing the servo 98, the lower end of the hollow spindle ||8 engaging the pulley |2| on the inner spindle IIS to retract the slide |22 for inserting the lens blank 20 in the work holder 2|. The servo 98 is then deenergized to permit the carriage to move upwardly against the stops under the action of the weights 92 and the

motors

44 and 88 are energized to rotate the polishing tool, the truing element, and the lens at diilerent speeds. At this time, the motor |28 is energized to feed the polishing tool slowly into engagement with the truing element and the slide |22 is permitted to move upwardly relative to the carriage and project the lens surface into engagement with the polishing tool. Such engagement continues for a predetermined time depending on the type of lens being ground. At the end of this time, the servo 98 is energized to retract the carriage and the slide for the insertion of another lens blank to be polished. If desired, the switches for controlling all of the motors and hydraulic servos may be centralized at a control panel |34 located conveniently on the machine frame.

It will be apparent that the machine above described is especially adapted for high production lens grinding since different degrees of grinding may be performed on a lens in a continuous operation and because the novel mounting of the

tool spindles

24 and 66 enables adjustments of the same to be made quickly and easily. By supporting the tool spindles at widely spaced points on opposite sides of the common plane of the work and tool axes 33 and 34, it is possible to avoid inaccuracies in the work caused by vibration and deflection of the machine parts during the grinding operations. Accuracy in finished lenses is further insured by the novel concentric arrangement of the truing element I I6 and the work holder 2| so that the machine may be set up for simultaneous truing and grinding operations by positioning only two axes, that ci the polishing tool ||5 and the common axis 34 of the lens and the truing element.

I claim as my invention:

l. In an abrading machine, the combination of, a frame, an annular truing element, means on said frame rotatably supporting said truing element, a work holder for supporting a workpiece within said truing element and rotatably mounted on said frame to turn the workpiece about the axis of the truing element, a spindle adapted to support an abrading tool on said frame for rotation about an axis lying in a plane including the axis of said truing element and said workpiece, means on said frame for moving said spindle axially to bring said abrading tool into engagement with said truing element, and means on said frame for moving said work holder axially relative to said truing element to bring said workpiece into engagement with said abrading tool.

2. In an abrading machine, the combination of, an annular truing element, means on said frame rotatably supporting said truing element, an abrading tool mounted on said frame for engagement with said truing element, a work holder for supporting a workpiece within said truing element and rotatably mounted on said frame to turn the workpiece about the axis of the truing element, and means on said frame for moving said work holder axially relative to said truing element to project said workpiece axially beyond the truing element and into engagement with said abrading tool.

3. In an abrading machine, the combination of, a frame, a work holder mounted on said frame to rotate about a iirst axis and adapted to support a workpiece, a hollow spindle mounted on said frame for rotation about a second axis lying in a plane including said rst axis, a rst abrading tool carried by said hollow spindle and comprising a plurality of arcuate portions angularly spaced around and extending along a circular path concentric with said second axis and disposed at a predetermined radius therefrom to intersect said iirst axis during rotation of the tool, an inner spindle disposed within and ro- -tatable with said hollow spindle, a second abrading tool carried by said inner spindle and comprising a plurality of arcuate portions extending along and spaced angularly around said path and intervening between the spaced portions of said rst tool, and means on said frame mounting one of said spindles for movement axially relative to the other spindle to bring said tools successively into engagement with a common zone of said workpiece intersected by said first axis.

4. In an abrading machine, the combination of, a frame, a pair of abrading tools mounted on said frame for rotation about a common axis and each having a plurality of arcuate portions spaced angularly around and extending along a common circular path having said axis as its center with the arcuate portions of one tool intervening between the arcuate portions of the other tool along said path, and means for selectively moving said tools relative to each other along said axis to bring said arcuate portions of the respective tools alternately into engagement with a common zone of a workpiece supported on said frame.

5. In an abrading machine, the combination of, a frame, an abrading tool rotatably mounted on said frame and comprising a plurality of angularly spaced elements disposed along a circular path, a second abrading tool mounted on said frame to rotate about the axis of said first tool and comprising a plurality of angularly spaced elements disposed along said path and intervening between thel elements of said iirst tool, and means for selectively advancing said tools axially relative to each other into engagement with a common zone oi a workpiece supported on said frame.

6. In an abrading machine, the combination of, a frame, a pair of abrading tools mounted on said frame for rotation about a common axis and along a common circular path concentric with said axis, each of said tools having a portion spaced angularly around said path from a portion of the other tool` and means for Selectively advancing said portions relative to each other along said axis to bring the respective portions alternately into engagement with a common Zone of a workpiece supported on said frame.

7. In an abrading machine, the combination of, a frame, a Carriage mounted on said frame for movement along a rectilinear path, a hollow spindle journaled in said carriage for rotation about an axis extending longitudinally of said path, a holder on one end of said spindle for supporting a truing element with the cutting surface of the same disposed radially outwardly from said axis, an inner spindle journaled in and movable axially relative to said hollow spindle, a work holder on said inner spindle adjacent said rst holder for supporting a workpiece within the radius of said truing element and turning the workpiece about the axis of the truing element, a third spindle adapted to support an abrading tool and journaled on said frame to rotate about an axis lying in a plane including the axis of said inner and outer spindles, mechanism on said frame for moving said carriage along said path to bring said truing element and said abrading tool into engagement with each other, and mechanism for moving said inner spindle axially relative to said hollow spindle to project said workpiece beyond said truing element and into engagement with the abrading tool.

8. In an abrading machine, the combination of, a frame, a rst holder for supporting an annular truing element, a work holder concentric with said rst holder for supporting a workpiece Within said truing element, an outer hollow spin-:lle journaled on said frame and supporting said rst holder to turn the truing element about its axis, an inner spindle `journaled in and movable axially relative to said hollow spindle and supporting said work holder to turn the workpiece about the axis of the truing element, a third spindle adapted to support an abrading tool for engagement with said truing element and journaled on said frame to rotate about an axis lying in a plane including the axis of rotation of said inner and outer spindles, means on said frame for rotating said spindles independently of each other, and means for moving said inner and outer spindles axially relative to each other to project the work surface of said workpiece into engagement with said abrading tool.

9. In an abrading machine, the combination of, a frame, an elongated hollow member, a spindle journaled in said member for rotation about an axis lying in a predetermined plane, a crosspiece secured to and extending transversely of said member with opposite ends of the crosspiece disposed on opposite sides of said frame, two supporting members on said frame disposed at opposite ends of said crosspiece and pivotally connected thereto to permit swinging of said spindle in said plane about an axis normal to the latter, a carriage mounted on said frame for movement toward and away from one end of said spindle, a second spindle supported by said carriage for rotation about an axis lying substantially in said plane with one end of the spindle adjacent said one end of the iirst spindle, and means :for tilting said carriage and said second spindle in a second plane perpendicular to said first plane to cause the axes of said spindles to intersect.

10. In an abrading machine, the combination of, a frame, a spindle, a member supporting said spindle for rotation about an axis lying in a predetermined plane, means pivotally mounting said member on said frame to permit swinging of said spindle in said plane about an axis normal to the latter, a carriage mounted on said frame for movement toward and away from one end of said spindle, a second spindle supported by said carriage for rotation about an axis lying substantially in said plane with one end of the spindle adjacent said one of said rst spindle, means on said carriage providing two abutment surfaces disposed at widely spaced points on opposite sides of said plane, a first stop mounted on said frame to be engaged by one of said surfaces as said carriage moves toward said one end of said first spindle, a second stop mounted on said frame and similarly disposed with respect to the other of said surfaces, and means to move at least one of said stops relative to its abutment surface independently of the movement of said carriage thereby to effect tilting of the carriage and intersecting of the axes of said spindles.

11. In a abrading machine, the combination of, a frame, a first spindle rotatably mounted on said frame with its axis lying in a predetermined plane, a carriage mounted on said frame for movement toward and away from one end of said spindle, a second spindle supported by said carriage for rotation about an axis lying substantially in said plane with one end of the spindle adjacent said one end of said first spindle, means on said carriage providing two abutment surfaces disposed at widely spaced points on opposite sides of said plane, a first stop mounted on said frame to be engaged by one of said surfaces 2 as said carriage moves toward said one end of said first spindle, a. second stop mounted on said frame and similarly disposed with respect to .the

5 and intersecting of said axes.

JOSEF DESENBERG.

REFERENCES CITED 10 The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 15 995,393 Witmer June 13, 1911 1,221,858 Hollands Apr. 10, 1917 1,224,169 Hice May 1, 1917 1,327,440 MacGregor Jan. 6, 1920 1,483,754 Svensson Feb. 12, 1924 2o 2,286,361 Goddu June 16, 1942 2,352,146 Desenberg June 20, 1944 2,482,485 Hutchinson Sept. 20, 1949 FOREIGN PATENTS 5 Number Country Date 11,985 Great Britain Oct. 8, 1885 199,312 Germany June 12, 1908 611,999 Great Britain Nov. 5, 1948