US2392478A - Hemispherical generator - Google Patents

Description

Jan. 8, 1946. A. J. HOLMAN HEM ISPHERICAL GENERATOR Fi'led Feb. 10 1943 7 Sheets-Sheet 1 INVENTOR.

fiz /umffi Jan. 8, 1946. A. J. HOLMAN r 2,392,473

' HEMISPHERIGAL GENERATOR Filed Feb. 10, 1943 7 Sheets-Sheet 2 Jan. 8, 1946. A. J. HOLMAN 2,392,478

HEMI SPHERICAL GENERATOR Filed Feb. 1o, 1945 7 Sheets-Sheet s i3,- 0 g Q) 14 2'2 2 4 A l v INVENTOR.

65 .flrilau'cffizmn 1946- I A. J. HOLMAN 2,392,478

HEMISPHERICAL GENERATOR Filed Feb. 10, 1945 7 Sheets-Shet 4 INVENTOR.

Jan. 8, 1946. A. J. HOLMAN 2,392,478

HEMISPHERICAL GE'NERATOR Filed Feb. 10, 1945 7 Sheets-Sheet 5 Jan. 8, 1946. A. J. HOLMAN 2,392,473

HEMISPHERICAL GENERATOR Filed Feb; 10, 1945' v Sheets-SheetB ll sammgg Jan. 8, 1946. A. J. HOLMAN 2,392,478

HEMISPHERICAL GENERATOR Filed Feb. 10, 1945 7 Sheets-Sheet 7 INVENTOR fi za' Patented Jan. 8, 1946 UNITED STATES PATENT OFFICE HEMISPHERICAL GENERATOR Arthur J. Holman, Brighton, N. Y., assignor t Bausch & Lomb Optical Company, Rochester, N. Y., a corporation of New York Application February 10, 1943, Serial No. 475,363

15 Claims.

My invention relates to apparatus for generating optical surfaces of revolution to either match exactly the contour of a true spherical test glass or be uniformly aspheric to a prescribed degree with respect to specific zones when compared to a true spherical test glass. It has been the particular object of this invention to provide apparatus for generating spherical surfaces having shorter radii of curvature than can be worked successfully on my former spherical generating devices described in Letters Patent of the United States No. 1,827,748 dated October 20, 1931, and in copending application Serial No. 465,605 filed November 14, 1942. The present structures, as hereinafter fully described, are so organized that any portion of a spherical surface up to a hemisphere, or even more than a hemisphere if desired, may be generated at any radius of ctu'vature ranging from a few inches down to a few thousandths of an inch. Surfaces of revolution, aspheric to a prescribed degree, may be generated consistently on structures organized so that the axes of oscillation and rotation of work and tool spindles do not intersect at a common point, as they do in structures organized to generate spherical surfaces, but one or more axes deviate both in degree and direction from the point of intersection common to the other axes.

Lenses having surfaces subtending large solid angles cannot be generated on structures such as I have described in the Letters Patent and pending'application hereinbefore referred to be cause these structures are not designed to permit oscillation of either work or tool about the center of curvature of a hemispherical tool. Lenses of relatively large diameter having surfaces appreaching a hemisphere in extent are'required in several types of high angular aperture military objectives for photographic purposes. Certain forms of microscope objectivecomponents are also hemispherical and these elements are often quite small in diameter. Between these extremes in diameter, there are many lens elements, used in objectives and eyepieces, the refracting surfaces of which subtend large solid angles. The present device is designed to generate such optical surfaces, the demand for which far exceeds the production capacity of the nations precision optical manufacturers.

This device is simple, compact, requires a minimum of skill and experience for successful operation, and it will produce rapidly and in quantities surfaces of uniformly consistent curvature because the structures are precision built and are organized to perform movements of both work and tool corresponding'exactly to the geometrical requirements of the surface to be generated. The device, when properly constructed, will give years of satisfactory service at minimum cost for maintenance. The structures are organized to permit removal of work for inspection and subsequent replacement, either in the same or in duplicate mechanisms, in proper position with respect to radius and center of oscillation, for further grinding or polishing. The'apparatus is well suited to operation in batteries for progressive stages of grinding and polishing.

My device may be best understood by reference to the accompanying drawings in which Fig. 1 is a View, in perspective, illustrating arrangement of structures to meet geometrical requirements for generating short radius spherical surfaces.

Fig. 2 is a detail showing means for removing hinge pin P so axis BB may be'swung to vertical position as indicated in Fig. 1.'

Fig. 3 is a partial vertical section in the plane of the axes of work and tool spindles showing spindle mounting means; Extreme angular posi:

tions of tool supporting structures are indicated in broken lines.

Fig. 4 shows work spindle with work mounted thereon.

Fig. 5 is a plan view of a complete hemispherical generator, the gear box -cover being removed to show gear'driving mechanism.

Fig.6 is a vertical section on line 6-6 of Fig. 5 showing the supporting and driving means'for the upper oscillating member.

Fig. '7 is a side elevation of my device (spindles standing vertically) with parts broken away to show gear driving means.

Fig. 8 shows work spindle and tool in extreme positions: work spindle tipped to extreme left and tool tipped backward all the way.

Fig. 9 is a front elevation of my device (spindles standing vertically) showing upper oscillating member in side elevation and an end view of lower oscillating member. l

Fig. 10 is a perspective view showing the form taken by the belt which drives the work spindle rotatively.

Fig. 11 shows work spindle and tool in extreme positions: work spindle tipped backward all the way and tool rocked to exereme left. i

Fig. 12 is an elevation showing work and tool spindle mounts and a hinge structure built into the upper oscillating member. v

Fig. 13 is a section on line |3-I3 of Fig. 12 showing details of the hinge structure.

.Fig. 14 is a'section on line u| -|4 of Fig. 12

- showing key means for driving work spindle.

Fig. shows work spindle and work mounted thereon of larger diameter than the spindle.

Fig. 16 shows the structures'of Fig. 12 with the spindle end of the upper oscillating member swung away from operating position.

Fig. 17 shows work spindle'in partial section.

general arrangement of structures suited to fulfill these requirements are illustrated in Fig. 1;

by proper selection of the means, amount and direction of decentering employed.

Referring now more specifically to the drawings, in which like reference numerals indicate like parts, I (Figs. 5, 7, and 9) is a cast metal base to which is attached by screws 2 the'gear box 3 (Fig. '7). An angular bracket 4, integral with gear box 3, projects from two adjacent side walls of the gear box and carries, at one end integral cylindrical housing 5 positioned parallel to that side wall of gear box 3 to which it is adjacent, and

An upper oscillating member D, overslung from a suitable base, is arranged to swing about the horizontal axis B-B. A lower oscillating mem-.

ber E, underslung from the base, is arranged to swing in a plane at right angles to the upper memberjD about'the'axis A-.-A' which lies in the same ally toward the tool Gfthe l'atter having'a concave spherical abrading surface.

Work sp ndle H andjtool spinde F are rotatably supported in the upper and lower osc llat ng'members respectively. Lower member E isshown as being h nged on brackets L supported 'on' a suitable base. Upper member D is s'hown 'a's being hinged at'one end on a bracket M fixed on the same base and to which it is adjacent.

at the other end integral cylindrical housing 6 Positioned parallel to that side wall of gear box 3 Cylindrical housin s 5 and '6, which areidentical, are so bored that the axes of their bores intersect at right angle and lie in a plane parallel to the finished surface on the bottom of base i.

Lightly press fitted within bores in the ends of cylindrical housing 5 (Fig. 6) are ball bearings 1 the inner races of which'are a light pres fit on accurately ground seats on hinge pin 8. The upper oscillating arm 9 carries at one end integral hub l0 which is bored to a press fit on one end of hinge pin 3 and is further secured thereon by a suitable taper pin. The opposite end of hinge at the other end one tilting bracket N swin able axisC- -C thereby openin 'the oscillating structuresso that work spindle H and work K.mount ed thereon. also tool spindle F, may be withdrawn .rr'cm the device.

When spherical surfaces are to be generated, the structures must'be so'organized that axes of oscillation AA and 3-3. also the axis of tool su orting spindle F and'the axisof work'sup port ng spindle H, all meet at' "a common p'oint which coincides with thebenter "of curvature'of the s herical abradin surface of the tool G. Consistently uniform spherical surfaces cannotbe made unless'the structures of the device" are machined and assembled with'precisio'ni When aspherie surfaces are 'to be generated, the structures must be soorganize'd that the axes of oscillation A-A and B-'B'and the axes of work spindle H and tool' spindle-"F do notall intersect at a common pointTThis condition may be brou ht about by arranging the structures so axis through a slot running lengthwise of. crank arm A-A will not be inthe same plane as axis B--B;

pin 8 carries snugly slidable thereon a pair of anti-friction bushings I l which journal the double grooved pulley E2, the latter being freely rotatable. shouldered against outer bushing II and keyed to prevent rotation on hinge pin 3 is adjustable crank arm IS. The crank end of hinge pin 8 is threaded and provided with lock nuts l4 by means. of which the parts mounted thereon are retained in position andball bearings I are preloaded.

Flanged anti-friction bearing bushing 15 is se. cured by screws [B (Fig. '7) to theouter'surface of.

one sidewall of gear box 3; An anti-friction bearing bushing ll'is' press fitted into a bore in the opposite wall of gear box 3 inexact alignment with bearing bushing: 15 andin these bush-.

ings pulley shaft 18 is journaled; Pulley I9 is pinned on the outer'end of shaft l 8 and serves as the means for actuating the complete mechanism. Within the gearbox 3, a helical gear 20 is 'pinned on pulley shaft 18 and meshing with helical gear 20 is helical gear 2| pinned on crank shaft 2'2,the latter standing at right angles to the pulley shaft and being 'journaled in anti friction bushings (Fig. 9) press fitted or held by screws in opposite walls of gear box 3. One endof crank shaft 22 (Figs. 5, '7, and 9) extends outwardly from gear box 3 andon this part of shaft 22 is pinned pulley 23 and crank 24. A connecting rod 25 is attached at one end to crank 24, by screw 26 where on the connecting rodrotates freely, and at the other end to adjustable crank arm l3 by means of screw 21 and nut 28 (Fig. 6). Screw 21 passes l3 and enters nut 28, the latter being flattened on two sides to fit in a slot on the back of crank arm l3 to prevent turning of the nut while loosening or tightening screw. '21 to adjust the effective 7 length of the crank arm. i

Within gear box 3 (Fig. 7) a spur gear 29 is pinned on pulley shaft l8, and meshing with spur gear 29 is spurgear 30 pinned on crankshaft 3|, the latter standing parallel to the pulley shaft and being journaled 'in anti-friction bushings press fitted in opposite walls of gear box 3. 0n

the end of crankshaft 3! extending outwardly from gear box 3' is pinned pulley 32 and crank 33.

' A' connecting rod 341s attached at one end to crank 33 by screw 35 whereon the connecting rod rotates freely. The other end of connecting rod 34 is attached to adjustable crank arm 36 by means of screw 31' and nut 38. The adjustable crank arm 36 is a duplicate of adjustable crank arm I3 and it is keyed and locked on hinge pin 39 in the same manner as hereinbefore described with respect to crank arm l3 and hinge pin 8. Hinge pin 39 carries a pair of anti-friction flanged bushings whereon is journaled the double grooved pulley 40 which is a duplicate of pulley l2. Hinge pin 39 is journaled in cylindrical housing 6 in the manner hereinbefore described for hinge pin 8 and cylindrical housing 5. n the end of hinge pin 39 opposite to crank arm 36 is press fitted and pinned integral hub 4| of lower oscillating arm 42.

Upper oscillating arm 9 (Figs. 3 and 9) has an integral cylindrical housing 43 the axis whereof stands at right angles to the axis of hub H3 in a bore wherein hinge pin 8 is press fitted. This cylindrical housing is bored so that the axis of this bore extended will intersect at right angles the extended axis of the hinge pin 8. A pair of precision ball bearings 44 the outer races of which are lightly press fitted in aligned bores in opposite end of cylindrical housing 43 journal the sleeve 45 which has end portions ground to a light press fit in the inner races of these ball bearings. Ball bearings 44 are retained in cylindrical housing 43 by end plates 46 which are attached and retained in position by suitable screws. fitted on sleeve 45 and set screwed thereto to prevent rotation on the sleeve. Work spindle 48 is closely fitted to the bore in sleeve 45 and there is just sufiicient clearance to permit the spindle to slide without binding. The lower or work mounting end of spindle 48 is tapered to clear the tool when the latter is rocked to the extreme positions as indicated in Figs. 3 and 11. Pin 49 (Figs. 3 and 4) is fixed in the side of work spindle 48 and fits in a slot in the upper end of sleeve 45 so the work spindle may be rotated by and may feed downwardly through the sleeve 45 as grinding of the work progresses. A lens blank 68 is fixed on the lower end of work spindle 48 by pitch or other suitable means. A stud 50 (Figs. 3 and 9) is fitted in a bore in boss on upper oscillating arm 9 and issecured therein by a set screw. A bracket 52 having a bore slidable upon the upper portion of stud 50 has integral arm 53 wherein is riveted pivot pin 54, the latter being in alignment with work spindle 48 and entering a conical seat in the upper end thereof. A helical spring 55 slidable on stud 5U bears at one end against bracket 52 and at the other end against knurled adjusting nut 55, the latter being tapped to fit on the upper threaded portion of stud 59. An idler bracket 51 (Figs. 5, 7, and 9) is secured by screws 58 to upper oscillating arm 9 and projects rearwardly therefrom over hinge pin 8, terminating in a transverse boss 59. Shouldered screws 69, threaded into opposite ends of transverse boss 59 serve to journalidler pulleys 6| which are in alignment with the inner groove of pulley l2 and. with pulley 47. A belt 62 is threaded over the inner groove of pulley I2, over idle pulleys BI and over pulley 41. A belt is threaded over the outer groove of pulley l2 and over pulley 23.

Lower oscillating arm 42 terminates incylindrical housing 63 (Figs. 3, 7, and 9). A sleeve 64 (Fig. 3) is journaled in precision ball bearings fitted into cylindrical housing 63 in the same manner as hereinbefore described in connection with sleeve 45 in upper oscillating arm- 9. H A pulley 55 is'fitted on and set screwed to the lower A pulley 41 is end of sleeve. 64. A tool spindle '66 is fitted in the bore in sleeve 64 with minimum clearance for free sliding and carries fixed on its upper end the concave tool 61. Spindle 66 is threaded at its lower end and for some distance below the tool supporting means near its upper end and lock nut 69 and knurled screw 10 are provided so that tool spindle 66 may be variously positioned in a vertical direction to bring the center of curvature of the abrading surface of tool 61 so it coincides exactly with the point of intersection of the axes of hinge pins 8 and 39. An idler bracket H (Fig. 7), just like idler bracket 51, is secured to lower oscillating arm 42 and extends rearwardly under hinge pin 39 to support idler pulleys 12 in align ment with the inner groove of pulley 49 and with pulley 65 (Figs. 5 and 9). A belt 13 is threaded over the inner groove of pulley 4!}, over idler pulleys I2 and over pulley 65. A belt 14 is threaded over the outer groove of pulley 40 and over pulley 32.

In Figs. 3, 5, 7, and 9 is illustrated a device suitable for generating spherical surfaces subtending large solid angles but the'diameter of the work is shown as smaller than the diameter of the work spindle. It is possible, therefore, to withdraw the spindle and the work mounted thereon through the spindle supporting sleeve, hence there is no problem involved in getting the work in and out of the device for grinding and for inspection and subsequent grinding and/or polishing. When the work is larger in diameter than the work spindle, as in Figs. 1, 12 and 16, the above procedure is no longer possible and provision must be made whereby the Work spindle supporting sleeve may be shifted out of alignment with the center of oscillation of the tool. The work spindle may then be withdrawn from the lower end of the work spindle supporting sleeve. It is essential, of course, that the positioning and alignment of the work piece on the workspindle remain unchanged during all grinding and polishing operations. It is necessary, therefore, to remove the work spindle with the work from the generator whenever the work is inspected or when it is to be transferred from generator to generator for progressive grinding and polishing.

In Figs. 12 to 16 are shown structures adapted to permit swinging the work spindle supporting end of the upper oscillating arm out of alignment with the center of curvature of the tool to allow removal of the work spindle and precision means for aligning these parts again after the work spindle has been replaced in the device. In this construction, the upper oscillating arm has two parts which are hinged together. The lower part :6 has integral hub 11 press fitted and pinned on hinge pin 8 and terminates, at the other end, in.

a three pronged circular hingestructure 78 (Figs. 12 and 13). The upper part 19 of the upper oscillating arm has integral cylindrical housing 80 at one end and at the other end is a two pronged circular hinge structure 81 which fits accurately into hinge structure 13, the two being pivoted on and clamped together by knurled screw pin 82 and nut 83, the latter being doweled to hinge structure l8 to prevent turning as screw pin 82 is tightened or loosened. A pair of dowel pins 84 are accurately fitted in holes through hinge structures l8 and 85 at suchrelative angular positions of the hinge structures that the axis of the work spindle mounted in cylindrical housing 80 will pass through the center of curvature of the abrading surface of the tool carried by the lower oscilin the end of cylinder 93.

lating arm. A curved bracket 85 fixed on lower part '16 'of the upper oscillating arm serves in "place of bracket '51 (Fig. 9), to support idler pulleys 6| over which belt 62 is threaded, and

another bracket 86 (Figs. 12 and 16) carrying idler-pulleys 81 is fixed on the upper part 19 of the upper oscillating arm. The function of brackets 85 and 86 is to maintain tension on belt 62 and prevent it from falling off pulley 41 when the upper part 19 of the upper oscillating arm is swung back for the purpose of removing the work spindle.

A sleeve 88 (Fig. 12) isjournaled within cylindrical housinglloin precision ball bearings, as previously described in connection with sleeve 45, and-within sleeve 88 is accurately fitted for free sliding thework spindle 89. On the lower end of the work spindle is mounted by pitch, or other suitable means, a lens blank 90 of larger diameter than spindle 89, and the upper end of the work spindle is provided with a conical recess wherein pin 54 may enter.

A keyway 9i ending in a deeper cylindrical depression 92 is cut into work spindle 89 (Figs. 15 and 17) Into a tapped hole in the side of sleeve 88 near its upper end is screwed the threaded cylinder 93 (Figs. 12 and 4) wherein is freely slidable the body of key pin 94, bothendsof which are of smaller diameter, the one to serve as a key inkeyway 9| in work spindle 89 and the other to pass through a bore A knurled head 95 pressed on key pin 94 serves as a means for withdrawing the key pin from keyway 9! against the pressure of helical compression spring 96 which surrounds the key pin and abuts against the end of cylinder 93 at one end and against a shoulder on the key pin at the other end. When the work spindle 89 is raised sufiiciently in sleeve 98, the end of keypin 94 enters the cylindrical depression 92 in the work spindle and the spindle is retainedin its elevated position out of engagementfwith the tool 91 the latter being supported as hereinbefore described on the lower oscillating arm.

Power to actuate my device is applied by belt to pulley l9. Rotation of pulley shaft' lfi causes crank shafts 22 and 3] to revolve because of their gear connection with the pulley shaft. The ratios of the spur gears 29 and 30 driving crank shaft 3! are slightly different from the ratios of helical gears 29 and 2| driving crank shaft 22, therefore the crank shafts will rotate at slightly diiferent relative speedsand there will'be a progressive phase shift between cranks 24 and 33. It follows, therefore, that upper oscillating arm 9, operated by crank 24 through connecting rod 25 and ad- 66, sleeve 64, pulley 65, belt 13,.d0uble groove pulley 40, belt 14 and pulley 32 which-is fixed on and rotates with crank shaft 3|. Pulleyfsizes may be selected to rotate work and tool at any desired relative rates; Also the rates of rotation of tool and work spindles with respect to rates of rotation of the respective crank shaft by which each is driven rotatively, may be varied byjchanging ratios of pulleys. rotation of work and tool spindles may be changed by substituting gears of opposite hand for helical gears 20 and 2|. e w

Thus the device hereinbefore described is capable of providing rotation and osclllation'of both work and tool in such manner and under such restraint that all movements may take place only about the center of curvature of the abrading surface of the tool. Moreover, a'simple change in pulley ratios, which may be made quickl and without dimculty by merely substitutingpulleys of different diameters, will provide a great range of relative'speeds of oscillation and rotation and hence an almost limitless variety of motion pattern in the abrading action between work and tool. All mechanisms herein described will fulfill the primary conditions for a hemispherical enerator as outlined'in connection with the description of the schematic structures illustrated in Fig. 1.

oscillating arm. The correct elevation for the I tool ma 'be determined easily as follows: A

justable crank arm l3, will be caused to swing.

back and forth at a slightly different rate and at right angles to the plane of oscillation of lower oscillating arm 42, the latter being driven by through the-belt 62.v Pulley 41, being fixed on work spindle supporting sleeve 45 (or 88), causes workspindle 48 (or 89) to rotate, thereby rotating lens blank 58 (or 99).. 111 like manner, tool 61 (or 9'!) is'driven rotatively through spindle spindle similar to the work spindle but having a pointed lower end just slightly rounded, is placed in the work spindle sleeve wherein it slides freely without appreciable shake. An indicator, attached tothe upper oscillating arm with it pin resting on the upper end of this special spindle, will show no variation in reading, as the mechanism is slowly operated by hand, when the center of the spherical tool'surface coincides with the center of oscillation. A work spindle to which is suitably attached a convex tool, turned true to the spindle and of the same radius as the concave tool, is inserted in the sleeve carried on the upper oscillating arm, and the spring mechanism for applying pressure on the end of the work spindle is swung into operating position, The oscillating mechanisms are set to meet the requirements of the 7 surface to be generated. Abrading material is applied as required to the spherical surfaces of the tools and the mechanism is power operated till each tool has genunder test glass inspection, the tool maybe elevated slightlyby loosening knurled'screw T0 and tightening lock nut 69. However, if the finishing tool is used only for final fine grinding, many lens surfaces may be finished before any tool adjustment is required. 1

In all surfaee generating devices the radius of The relative direction of oscillation is determined by theposition ofth lap with respect to the center or axis ofosc'ill'ation. When polishing with a pitch polisher, or other yielding type of polisher, the radius of oscillationis generally determined by fixing the radius of oscillation of the work spindle by some simple locking device which is set at the termination of the final fine grinding operation. The tool spindle may then be removed and a polisher spindle carrying a pitch polisher substituted for the tool spindle.

While I have described and illustrated some forms which the present invention may take, it will be obvious to those skilled in the art that other-structures may perform the necessary functions equally well. The fundamental requirements which a hemispherical surface generator should satisfy are illustrated in Fig. 1 and the mechanical symmetry of the structure has been hereinbefore fully disclosed. The i appended claims are drawn sufficiently broad to coverany and all structures possessing such symmetry and it is intended that the claims be so interpreted.

4 Having thus fully described my device, what I claim is:

l. A generator for short radius spherical surfaces comprising a base, a pair of hinge pins disposed at an angle to each other and supported on said base, a lower oscillating member hingedly underslung from one of said hinge pins, an upper oscillating member hingedly overslung from the other of said hinge pins, a tool, means for rotatably mounting said tool on one of said oscillating members, means for rotatably mounting a work piece on the other of said oscillating members,

actuating means for oscillating said members on said pins, respectively, and for simultaneously rotating said mounting means for said tool and work piece to generate a desired surface on said work piece, and a hinged bracket on said base on which said work piece mounting means is movably supported for separating said tool and work piece and clearing said Work piece mounting means for detachment from said bracket Without removing said work piece from its said mounting means.

2. A generator for very short radius spherical surfaces comprising a base, a pair of hinge pins disposed at an angle to each other and supported on said base, a lower oscillating member hingedly underslung-from one of said hinge pins, an upper oscillating member hingedly overslung from the other of said hinge pins, a tool spindle mounted in one of said oscillating members, a work spindle slidably mounted in the other of said oscillating members, actuating means for oscillating said members on said pins, respectively, and simultaneously rotating said spindles to generate a desired work surface, and a spherical tool mounted on said tool spindle adapted and arranged to oscillate about its center of curvature, said work spindle having a diameter greater than that of the work mounted thereon so that said work spindle may be slidably removed from its mounting in said member without detaching said work from said spindle.

3. A hemispherical surface generator comprising a rotatable work spindle, a rotatable tool spindle, a spherical tool fixed on said tool spindle, means for swingably supporting said tool spindle to hinge upon an axis intersecting the axis of said tool spindle at right angles at the point corresponding to the center of curvature of said tool,

means for swingably supporting said work spindle to hinge upon an axis intersecting the axis of said work spindle at right angles at the" point corresponding to' the center of curvature of said tool; said'hinge axes of said tool and work spindles being arranged to extend substantially perpendicul'arly to each other, actuating means for simultaneously swinging and rotating said spindles to generate a desired work surface, means for feeding said work spindle radially toward said tool, and means for swinging the axis of rotation of said work spindle about an axis parallel tothe axis of oscillation of said tool for the'purpose of withdrawing the-work on said work spindle from said tool. Y

4. A short radius spherical surface generator comprising a' rotatable work spindle whereon work may-be mounted, arotatable tool spindle whereon aspherical tool is mounted, independent means for rotating said work and tool spindles, independent means supporting said spindles for oscillation about the center of curvature ofsaid spherical tool in planes at right angles to each other, respectively and actuating means for oscillating said spindles to generate a desired work surface, said spindle supporting means having an amplitude of oscillation adapted for generating hemispheres of any required minimum diameter, greater than zero. i

5. A short radius spherical surface generator comprising a rotatable work spindle whereon work may be mounted, a rotatable tool spindle whereon a spherical tool is mounted, independent means for rotating said' work and tool spindles, independent means including overslung and underslung members whereby said spindles, respectively, are supported to oscillate in planes at right angles to each other about the center of curvature of said spherical tool, for generating said surface and means supporting said work spindle for movement to and from position for generating oscillation to permit removal of said work spindle for inspection or, work mounted thereon and replacement of said work spindle and work in exactly their respective former positions for subsequent grinding and polishing operations.

6. A'short radius spherical surface generator comprising a rotatable work spindle whereon work may be mounted, a rotatable tool spindle whereon a spherical toolis mounted, independent means for rotating said work and tool spindles, independent means including overslung and un derslung members whereby said spindles, respec tively, are supported andoscillated in planes at right angles to each other about the center of curvature of said spherical tool, and means for 7 locking the relative positions ofthe axes of oscillationduring operation and for releasing one of said members'from its axis of oscillation to per- $it removal and replacementof said work spin- 7.111 a hemispherical surface generator, the combination of a rotatable work spindle whereon work may be mounted, a rotatable tool Spindle whereon a spherical'tool is mounted, means sup porting said spindles for oscillation in planes at right angles about the center of curvature of said spherical tool, means for rotating said spindles, and means for oscillating saids'pindles at slightly different frequencies for generating said'surface on the work with a "highly varied cyclic abrading pattern;

8. Inia hemisphericalsurface generator, the combination of a rotatable work spindle whereon work may be mounted, a rotatable tool spindle whereon a spherical tool is mounted, means supporting said spindles for oscillation in planes at right angles about the center of curvature of said spherical tool, and meansfor oscillating said spindles from said base for oscillating in planes at right anglesto each other about the center of curvature of said spherical tool for generating saidsurfac e with a highly varied cyclic abrading pattern, hinged mounting means whereby said work spindle is movable out of alignment with the center ofcurvature of'said spherical tool so that; said work spindle may be removed from its supporting means without removing the work from said spindle, and means for locking'said hinged means in operating position so that the axis of said work spindle will pass through the 1 center of curvature of said spherical tool.

10. A short radius spherical surface generator comprising aibase, a tool spindle on said base, a toolfixed onsaid spindle having an abrading surface approximating a hemisphereiin extent, a

work spindle on said base adapted to have fixed thereon a lens blank with an optical surface approximating ahemisphere inextent, means for rotating said tool spindle and for simultaneously oscillating the same about a fixed axis perpendicular to theaxis of said tool spindle, and means for rotating said work spindle and simultaneously oscillating the same about a fixed axis 'perpene dicular tothe axis of said work spindle and exten in at an angle to. the axis cf oscillation of saidtool spindle, all ofsaid axes being arranged to extend through the center of curvature of the abrading surface of said tool, for generating said surface with ,a highly varied cyclic abrading pattern,-q' U V -lLfA short radius spherical surface generator comprising a base; stationary bearings on said base, members oscillating in said bearings about intersecting axes, a tool spindle having a sphericaltool fixed thereon and mounted in one of said 1 members for rotation about an axis perpendicular to the axis of oscillation of said member, a work spindle adapted to have a spherical lens blank lens blank fixed thereon and mounted in the bearing of the other of said members for rotation about an axis perpendicular to saidaxis of oscillation of said member, all of said axes being arranged to extend through the center of curva ture of said tool, said spindles beinglongitudinally slidable in said member bearings for insertion and removal therefrom, releaseable means for retainingsaid spindles in said member bearings, one of said members comprising movably V 7 connected parts for swinging the spindlethereof away from the other of said spindles, to clear said spindles for removal bodily from said members,

fixed thereon and mounted on theother of said members for rotation about an axis perpendicular to said axis of oscillation of said'member, all

with a highly varied cyclic abrading pattern.

12. A short radius spherical surface generator comprising a base, stationary bearings on said base, members oscillating in said bearings about bearing, a tool spindle having a spherical tool fixed thereon and mounted, in the bearing of one of said members for rotation about an axis perpendicular to said axis of oscillation of said memher, a work spindle adapted to have a spherical W intersecting axes and each formed with a spindle and means for rotating said spindles and simultaneously oscillating said members to generate said surface with a highly varied cyclic abrading pattern.

13. In a device of thecharacter specified, a base, a pair of hinge pins disposed at an angle to each other and supported on said base, a lower oscillating member hingedly underslung from one of said pins, an upper oscillating member hingedly overslung from the other of said pins, a tool spindle rotatably mounted on one of said members, a tool on said spindle, a work piece spindle rotatably mounted on the other of said members,

actuating means for simultaneously and continuousl oscillating said members and rotating said spindles to generate a desired work surface, and means supporting said upper oscillating member for swinging movement about an axis parallel tothe axis of the hinge mounting of said lower oscillating member whereby said spindles may be quickly and widely separated 'for mounting and removal of said tool and Work piece. I

14. A hemispherical surface generator comprising a base, a bracket hinged on said base, an upper oscillating member hingedly overslung on said bracket, a lower oscillating member hingedly underslung on said base to oscillate about an axis parallel to the axis on which said bracket is hinged, a tool having'a curved abrading surface, means for rotatably mounting said tool on one of said members, means for'rotatably mounting a work piece on the other of said members for cooperation with said tool, said members being mounted to oscillate about axes intersecting each other at the centerof curvature of the abrading surface of 'said tool, actuating means for rotating said tool and work piece, and actuating means 15. In a hemispherical surface generator, the V combination of a base, a bracket hinged on said base, an upper oscillating member hingedly overslungon said bracket, a lower oscillating member hingedly underslung onsaid base to oscillate about an axis intersecting the axis of oscillation of said upper member, a tool, means for rotatably mountingsaid tool on one of said members, means 'for rotatably mounting a work piece on the other of said members, actuating means for simultaneously and continuously oscillating said members and rotating said mounting means for said tool and work piece to generate a desired work surface, and means for releasably locking said bracket and upper member in generating po-' sition whereby said bracket and member may be swung to'position for mounting and removal of saidlmounting means for said tool and work piece.

ARTHUR J.IHOLMAN.I

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