US2020709A - Grinding machine - Google Patents

Description

Nov. 12, 1935. c. v. WALTER GRINDING MACHINE Filed March 10, 1931 15 Sheets-Sheet 1 I INVENTOR Charla: 1 Walter.

M ATTORNEY Nov. 12 1935. c. v. WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1951 15 Sheets-Sheet 2 mm M INVENTOR Charles M Welter.

M3. ATTORNEY NOV. 12, 1935. C, v WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1931 15 Sheets-Sheet 5 .7 Q 4037/ I11 I G INVENTOR Charles 1 We lter.

' M ATTORNEY.

Nova 12, 1935. c. v. WALTER GRINDING MACHINE Filed March 10, 1931 15 Sheets-Sheet 4 INVENTOR Charles M Wat fer.

ATTORNEY c. v. WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1931 15 Sheets-Sheet 5 INVENTOR Charles V. Walter m ATTORNEY 1935- c. v. WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1931 Q5 Sheets-Sheet 7 y '7; 9a 99 J 455 X 94 If) a a H g g /74 i i m 1 M1 um! 49 x\ J 490 45.9

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6 INVENTOR Charles I! Walter. BY swgwbkm m ATTORNEY Nam 12, 1935..

C. V. WALTER GRINDING MACHINE Filed March 10, 1931 15 Sheets-Sheet 9 a I 307 iii f MW j; Z Q/ 41 I A! A j 2% E 4 O INVENTOR Charles I! Walter. X610 12.56 BY smaadafium.

nix ATTORNEY Nov. 12,

C. V. WALTER GRINDING MACHINE Filed March 10, 1951 15 Sheets-Sheet 10 Rm}, ATTORNEY Nov. '12, 1 935.

GRINDING MACHINE Filed March 10, 1951 15 Sheets-Sheet ll iii INVENTOR (bar/e5 ll W31 len BY SMAMJXA 3 mm,

m ATTORNEY c. v. WALTER 7 2,020,709

Nov. 12, 1935. v c. v. WALTER 2,020,709

GRINDING. MACHINE Filed March 10, 1931 15 Sheets-Sheet 12,

Q N E x E S 1 INVENTOR Charles 1/. Walter.

M ATTORNEY Nov. 12, 1935. WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1931 15 Sheets-Sheet l3 INVENTOR 2.97 fiflYgr'les 1 W81 2" er.

M3, ATTORNEY NOV. 12, 1935. Q v WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1951 l5 Sheets-Sheet l4 2114/1 llll k l gllllflll' INVENTOR BY swam-MSW- N; AITORNEY NOV. 12, 1935. c v WALTER 2,020,709

GRINDING MACHINE Filed March 10, 1951 15 Sheets-Sheet 15 l N V E N T O R Charles 1 Walter.

m ATTORNEY Patented Nov. 12, 1935 UNITED STATEfi "PATENT OFFICE 27 Claims.

This invention relates to grinding machines, and more particularly to machines for beveling and finishing ofi the edges of watch glasses or disks of glass or other material.

In the preferred embodiment of my invention, the beveling of the disk is accomplished by holding and rotating the disk with its edge in contact with an approximately flat grinding surface of annular shape, which forms a part of a rotary grinding wheel. Suitable means are provided for holding the disk at the proper angle to the grinding surface to give the required angle of bevel, and this holding means not only rotates the disk about the axis of the disk but also moves or swings it in a direction toward the center of the grinding wheel so that the entire width of annular grinding surface is traversed during the operation.

The grinding wheel also carries a second grinding surface inside of and concentric to the above mentioned surface and the swinging movement of the disk holder, after carrying the disk inwardly over the first mentioned surface, carries it on to the second surface, which, in the preferred embodiment of my invention, is a strip of felt which serves to polish the beveled edge of the disk.

If desired, also, I may provide the face of the grinding wheel with three or more concentric, annular grinding surfacesof different degrees of fineness which act successively on the disk to produce rough and fine grinding and polishing. After passing over the successive grinding or polishing surfaces, the beveled disk then preferably passes along the surface of a second grinding wheel, which has the effect of taking off the sharp edge or acute angle of the bevel. The particular arrangement of the two grinding wheels for accomplishing the results above described is one of the features oithe present invention and will be described in detail hereafter.

Also, in the preferred embodiment of the grinding machine herein disclosed, I have provided means by which the disk holder automatically receives the disk to be beveled and oncompleticn of the beveling and finishing operations, automatically discharges the disk to a suitable receiving apparatus, such as a conveyer. The machine arrangement illustrated comprises what be termed a receiving or pick-up station at which the disk is received by the holder and a discharge station, at which the finished disk is discharged. These two stations are located at diiierent points about the axis of the grinding wheel and the disk holder, during the grinding operation, is moved around the axis of the grinding wheel from the receiving to the discharge station, the disk holder thus having a planetary motion with respect to the axis of the grinding wheel.

In practice, I employ a plurality of disk holders all concurrently cooperating with the grinding wheel. These several holders are located at equally spaced points around the grinding wheel and all move simultaneously around the axis of the wheel, thus passing successively by the receiving station, traveling around the grinding wheel, and passing successively by the discharge station, the arrangement being such that the disks held by a number of successive holders will be undergoing successive stages of grinding, while another holder will be receiving a new disk, and yet another holder will be discharging a disk which has been ground.

In practice, I employ air suction for holding the disk to the holder, and my invention contemplates, among other features, the provision of an improved air system whereby the air pressure at the several disk holders may be automatically controlled for releasing and applying the suction, for discharging and receiving of disks, respectively. Also, I provide the air system with improved automatic cut-offs designed to relieve the suction from any disk holder in case the disk or lens held thereby is broken, or if, for any other reason, the disk does not make a proper sealing contact with the holder, as will be more fully described and explained hereafter.

At the receiving station, I preferably employ a suction operated pick-up device which auto matically picks up the disks to be ground from V a stack of disks, and transfers each disk to the disk holder of the grinding machine while the latter is moving toward its initial grinding position. In certain cases it may be desired to have adisk operated upon by a plurality of grinding machines, and in this event a suction pick-up device of described character may be employed to transfer the disk from one machine to another.

From the above brief description it will be seen that I provide a disk beveling machine which is entirely automatic in operation, which is designed to operate on a plurality of disks simultaneously, and wherein each disk is subject automatically to a series of grinding and finishing operations.

The machine disclosed in the accompanying drawings embodies numerous improvements in its various parts, among which are: an improved means for insuring a constant angle of bevel of the disks; means for insuring that the disks shall, 55

if desired, be ground to one bevel and to one outside diameter; adjusting means for changing the angle of bevel and diameter, as desired; means for adjusting the grinding wheel to compensate for wear of the abrasive material, which adjustment may be automatic or hand operated, as desired; an improved means for maintaining the moving parts oiled particularly in conjunction with an air system wherein danger of sucking oil into the air system is eliminated.

Among the other objects of my invention is the provision of a machine of the character described, which is relatively simple in construction, strong and durable in operation, which does not require the exercise of high technical skill for its operation, and which requires the minimum attention of the operator.

Numerous other objects and advantages of my invention will appear from the following description taken in connection with theaccompa'nying drawings, wherein:

Figure 1 is a side elevation of a grinding machine embodying one form of my invention, certain of the parts being omitted for the sake of clearness,

Figure 2 is a side elevation, looking from the right of Figure 1, the disk holder head being omitted,

Figure 3 is a top plan view of the machine, showing the disk holders arranged around the main grinding wheel, and showing, also, a portion of the pick-up mechanism,

Figure 4 is a central, vertical, sectional view taken on the line 4-4 of Figure 3, certain of the parts being broken away and others being shown in elevation,

Figure 5 is a diagrammatic plan View of the hold the .disk in positive engagement with thecutting wheel.

Figure 8 is a similar view, but showing the disk raised from the outer grinding surfaces of the main wheel, this occurring after completion of the grinding operation and. while the disk is being moved outwardly over the other grinding surface toward the discharging station,

Figure 9 is a view still further enlarged, of the disk in contact with the grinding wheel, showing how the relative arrangement of grinding surfaces on the main and auxiliary grinding wheels serverto shape the edge of the disk,

Figure 10 is a horizontal, sectional detail view, taken on the line iii-40 of Figure 1, certain of the parts being shown in elevation,

Figure 11 is a'vertical sectional detail view,

' taken on the linel iH of Figure 10, and showing part of the gearing used for adjusting the height of the main grinding wheel,

, Figure 12 is a view similar to Figurehll, but

I taken on line 12-42 of Figure 10, and showing a part of the driving means for giving to the disk-holder heads a planetary movement around theaxis of the main grinding wheel. 7

Figure 13 is a fragmentary, vertical, sectional matic cut-oif valve for relieving the he ,of suction when a defective is received View, taken on the line l3-l3 of Figure 3, and showing a portion of the main grinding wheel and, in addition, the auxiliary grinding wheel in grinding contact with the edge of the disk, together with the mounting for the auxiliary wheel,

Figure 14 is an enlarged fragmentary sectional view similar to Figure 4, showing portions of the grinding machine and pick-up mechanism, with certain of the operating parts in section,

Figure 15 is a diagrammatic view of the cam used for operating the clutch shown in Figure 14, which is connected between the source of power and the gearing for rotating thedisk about its own axis while the disk is in contact with the grinding, wheel.

Figure 16 is a vertical s c ional view through a disk holder head or assembly showing diskholder nozzles of the grinding machine and pickup mechanism holding a disk between them in the act of transferring the disk from the pick up nozzle to a disk-holder nozzle of the grinding machine.

Figure 17 is a sectional view taken on the line il-llsof Figure 16, and showing part of the transmission mechanism employed for rotating the disk about its own axis,

Figure 18 is a vertical sectional view taken on the line l8-l3 of Figure 16, showing a portion of the air suction passage from the disk holder nozzle. 7

Figure 19 is a detail vertical sectional view, taken on the line iii-49 of Figure 16, and showing the actuating cam for raising the disk off from the grinding wheel after completion of the grinding operation as it is moved outwardly toward the discharge station,

Figure ZO is a horizontal sectional View, partly broken away, taken on the line e-'iil of Figure l, V

and showing the segments employed for rotating the disk-holder heads or asemblies about their vertical axes so as to swing the disk inwardly and outwardly across the grinding surfaces, 7

Figure 21 is a sectional View, taken on the line 2!- 2l of Figure 3 and showing parts of the pick up mechanism in elevation, V

Figure 22 is a detailed view of the means for lifting a stack f disks toward the ick-up nozzle in order that the nozzle may pick up the top disk of the stack for transfer to the disk holder of the grinding machine,

igure 23 is a diagrammatic showing the grinding machine ds holder and pick-up nozzles in their relative positions prior to the ransfer of the disk from the pickup to the grinding nozzle Figures 24, 25, and 26 are views of the structure shown in Figure 23, but showing the parts in the positions which they occupy successively in transferring the disk from the pick up to the grinding machine nozzle,

Figure 2'? is a detailv horizontal sectional view, taken on the line ill-21 of g we, and showing a portion of the suction air passage of a holder assembly, including part of a control valve for applying andremoving the suction as the disk is respectively received by the disk holder nozzle, and subsequently discharged after the grinding operation; and also showing a portion of the auto the nozzle,

Figure 28 is a vertical sectional view taken on r the line 28-28 of Figure 27,

Figure 29 is a side elevation ofthe structure shown in Figure 23, looking from the right and showing the operating means for the control valve,

Figure 30 is a view similar to Figure 29, but showing the control valve in a different position,

Figure 31 is a perspective view of parts of the control valve, separated from one another to show the internal air passages,

Figure 32 is a sectional view on the line 32-32 of Figure 2?, showing the automatic cut-off valve and passages leading thereto,

Figure 33 is a detail. horizontal sectional view, taken on the line 3333 of Figure 4, and showing the stationary lugs against which the control valve actuator impinges in the act of cutting off and applying the suction,

Figure 34 is similar to Figure 29, but shows the relative position of the parts prior to cutting off the suction,

Figure 35 is a diagrammatic view, showing the suction passages from the pick up nozzle to the valve for controlling the pick up suction, together with the cam actuated operating means for the pick up control valve,

Figure 36 is a sectional view on the line Ma -35 of Figure 35, showing the automatic cut off valve for the pick up nozzle,

Figure 37 is a sectional view, taken on the line 3l-3l of Figure 35, and showing a portion of the suction passage through the control valve for the pick up nozzle,

Figure 38 is a sectional View on the line 3838 of Figure 35, showing the means for holding the air coupling at the end of the pick-up nozzle shaft from rotating while at the same time permitting the shaft to be moved longitudinally.

Figure 39 is a side elevation showing the modification of the actuating means for adjusting the height of the main inding stone.

Figure 40 is an elevation of the structure shown in Figure 39, viewed from the right; and Figures 41 and 42 are diagrammatic views for transferring a disk from one grinding mechanism to another.

Referring to Figures 1 to 4, the grinding machine A comprises a Wheel B adapted to be rotated by means of a shaft C in a horizontal plane. Mounted at the outer edge of the wheel B is an annular grinding stone C, and also mounted on the wheel B and located inside of the stone C is an annular strip of felt D, this strip being posi tioned in substantially the plane of the upper surface of the stone C. Located above and eccentric to the axis of grinding Wheel B is a second grinding wheel F which has a lower annular grinding surface G, shown more clearly in Figure 13. Wheel F is carried by a vertical shaft H, shown in Figure 13.

Adapted to revolve around the axis of the grinding wheel B is a turn table J, upon which are mounted a plurality of disk holder heads or assemblies, ten in number and indicated generally by the reference character K. These disk holder assemblies each comprise a suction disk holder L, which is carried by a frame M,mounted to rotate slightly about a horizontal pivotal axis N, shown more clearly in Figure 14. The disk 0, which may be a watch glass, shown, for example, in Figure 14., is held by suction against a seat P of the disk holder.

It will be noted that due to the location of the pivotal point of the frame M, rotation or tilting of the frame M will cause the glass disk 0, carried by the disk holder, to be raised and lowered with very little change of the angle of the disk to the vertical.

The frame M is mounted on a supporting structure Q, which, in turn, is rotatably mounted on the turn table J so as to swing about a vertical axis Q, the construction and arrangement being such that rotation of the structure Q serves to swing the disk holder in a horizontal plane, swinging the disk toward or away from the axis of the main grinding wheel B.

Reference character R represents gearing mounted partly in the frame M and partly in the supporting structure Q. This gearing is designed to be operated by a vertical shaft S, whose axis is coincident with the axis Q of the structure Q. Gearing R serves to rotate the disk 0 about its own axis, as will be more fully explained hereafter.

From the above brief description it will be apparent that the disk 0 is supported in such a manner that it may be rotated about its own axis through the gearing R, and that, by reason of the pivotal connection at N, between the frame M and supporting structure Q, the disk also may be raised and lowered. Furthermore, by reason of the rotatable mounting of the structure Q on the turn table J, the disk may be swung toward or away from the axis of the main grinding wheel, and also by reason of the rotatable character of the turn table J the disk 0, with the entire disk holder assembly, may be rotated completely around the axis of the grinding wheel B.

In the grinding machine shown in the drawings there are illustrated means for imparting to the disk all of the motions above described, and in Figures 5 to 9, inclusive, I illustrate motions of the disk during the complete cycle of operations, by indicating different positions of the disk holder and disk. The position of the holder and disk about the axis Q as the turn table J is rotated are shown in Figure 5 and indicated by the reference characters Pi to PIB, inclusive.

At the position Pl the disk is at the receiving station, where the disk holder has just received its disk from the nozzle X of a pick-up mechanism, designated generally by the referencc character T in Figures 3 and 4.

In this position the disk holder extends outwardly in a substantially radial plane from the axis of the wheel B in the position shown, for example, in Figure 4.

The turn table, as well as the wheel B are indicated in Figure 5, as rotating in a clock-wise direction. Rotation of the turn table serves to move the axis Q of the shaft S, which is the axis about which the structure Q rotates on the turn table downwardly and toward the left from the position P in Figure 5. Simultaneously the structure Q is turned about this axis so as to swing the disk holder to the position P2, where the disk 0 is about to engage the upper surface of the grinding stone C. The angle between the disk and the stone is approximately 60, as shown, for example, in Figure 9. It will be understood, however, that by suitable adjustment of the parts this angle may be changed as desired. Further operation of the parts moves the disk holder to the position P3, in which it will be seen that the edge of the disk 0 has travelled partly over the width of the annular grinding stone 0, the lower edge of the disk, during this motion, re maining in grinding contact with the top of the stone, and because of rotation of the disk about its own axis by the gearing R, the disk is ground around its entire edge at an incline, as indicated in Figure 9.

At P4, P5, and P6, I show subsequent positions of the disk and disk holder from which. it appears that, as the turn-table rotates, the disk moves inwardly across the grinding stone C.

In position P! the grinding of the disk is complete and the disk is moved inwardly on to the annular strip of polishing felt D.

In the position P8 the disk is shown as having moved partly across the felt, the felt serving to polish the ground bevel surface.

In position P3 the disk is moved inwardly entirely across the strip of felt D and is about to move under the second grinding wheel F.

In Figures 7, 9, and 13 I show the disk in engagement with the lower annular grinding surface G of the wheel F, this being substantially the position of the disk at P98 in Figure 5.

During the passage of the disk from position P3 to PS, the weight of the disk holder and the frame M, acting about the pivotal point of the frame M, has served to press the disk at its edge against the grinding and polishing surfaces of the wheel B. As the disk passes inwardly off from the felt strip to position PS, the frame M, disk holder, and disk swing downward by gravity a short distance, this downward motion being halted by a device, indicated by the reference character U, in Figure 7, which determines the elevation of the axis of the disk as it moves under the second grinding wheel F.

The second grinding wheel F is vertically adreduce the diameter of the disk somewhat and the vertical adjustment of the grinding wheel F and the device U is such as to give the finished disk the required diameter.

In position PM the disk is shown as it is about to pass from under the grinding Wheel F, and it will be noted that at this time the disk holder is approximately radial to the axis of the grinding wheel B.

Immediately after passing from position Pll, the supporting structure Q is rotated with respect to the turn table J so as to turn the disk holder toward the position PIZ, from which it '11 be seen that the disk is now being carried out rdly with respect to the axis of grinding wheel B. This turning movement causes the disk to move back onto the felt D and after the disk has traversed the felt a second time, the device U, which serves as a stop to the downward swinging movement of the frame M, operates to swing this frame upwardly into a position shown diagrammatically in Figure 8, thus raising the disk above the level of the grinding surface. Thus the disk in moving outward does not contact with the surface C.

PI3, PM, and Pl show subsequent positions of the disk holder, the holder continuing its outward rotation until, in the position PIG, the

holder extends radially outward from the axis of the wheel B.

manner which will be described more fully in detail, to receive a new disk to be ground.

Grinding wheels, drive, and adjustment The main grinding wheel B comprises two castings,one, a casting i El, having a central hub portion ll, secured to the upper end of the vertic'al shaft C, and an outer portion l5, having an annular socket l6, designed to hold the grinding stone C, (see Figure 4). Between the hub. H and the outer portion Hi, the casting l0 forms an intermediate chamber, or space II, in which is located the second casting IS. The upper portion of the hub H is screw-threaded, as indicated at 20, so as to permit the casting I9 to be screwed on to hub portion of the casting I0. The two castings are rigidly secured to one another 'by a screw device 22, consisting of a tapered key 24, fitting a slot in the threaded hub II, and engaging outwardly against the wall 24' of a slot in the casting I9. The key 24 is pressed downwardly so as to engage tightly in the slots by means of a bolt 26, threaded through the key and into the casting 19, thus holding the casting I9 formed with a seat for receiving the annular strip of felt D. It will be seen from Figure 4 that the outer edge of the casting l9 and felt D are spaced somewhat from the inner face of the stone C, thus permitting the water supplied to the stone C, during the grinding operation, to flow between the stone and felt into the chamber H, from which it finds its exit through one or more openings 32 in the outer face of the casting III.

From the openings 32 the water flows into an annular trough 35 formed in the turn table J, and from this trough flows through one or more tubes 36, into a second annular trough 37, formed in a stationary casting 38, rigidly secured to a column casting 39, forming part of the stationary frame of the machine.

The trough 31 communicates by means of a bore 4| with a passage 42 in the casting 39 and passage 42, in turn communicates with a pipe, or other conduit 44, from which the water may be discharged into a suitable drain.

It will be seen that castings l0 and I9 are connected'to one another in such a way that the casting l 9 may be raised and lowered with respect to the casting II] by removing the locking device 22 and turning the casting IS on the hub II, and in this manner the elevation of the felt I0 with respect to the stone C may be adjusted. When grinding surfaces are employed of different material which wear down at different rates, this relative adjustment may be employed to maintain the grinding surfaces at substantially the same level.

The main grinding wheel formed by the castings l0 and I9 may be adjusted vertically with respect to the turn table J, upon which are mounted the central disk holders. For this purpose I provide a vertically movable and nonrotatable sleeve 50, which surrounds the shaft C, and serves to support the rotating grinding wheel through a ball-bearing 5| between the upper end of the sleeve 50 and a shoulder 52 of the shaft C, (see Figure 4). The sleeve 50 is keyed to a slide in the stationary column 39, and is adapted to be raised and lowered by an internal screwthreaded gear 54 which engages external screwthreads formed at the bottom of the sleeve'50.

Gear 54 is held against a vertical movement between the casting 39 and a casting or bolster plate 56, forming part of the stationary structure of the machine and supported by feet 68 from the base 69. Gear 54 is mounted to rotate in ball bearings 51 in a central portion of the bolster casting 56. The gear 54 is rotated by means of a spur gear 58, shown in Figure 11, which engages the outer teeth 59 of the gear 54. Spur gear 58 is secured to a vertical shaft which carries at its lower end a worm gear 60 operated by a worm 6| secured to a horizontal shaft 62 which extends outwardly through a side wall of the bolster plate, as shown in Figures 2 and 10, to a hand wheel 56. By turning the hand wheel 66, the gearing 62, 68, 58, 54 is operated, and the elevation of the grinding wheel B adjusted.

Vertical adjustment of the grinding wheel B may be necessary to take up for wear of the grinding stone C, also in certain machines for changing the angle of bevel, or changing the vertical distance between wheels B and F. In this connection it is to be noted that the final diameter of the disk is determined by the elevation of the wheel F and adjustment of the devices U, each of these devices being independently adjustable to limit the elevation of the disk as it passes under the grinding wheel F. By making the devices U independently adjustable, in a manner to be explained hereafter, it is possible to so adjust the final diameter of each disk that all disks delivered by the machine will be of uniform diameter.

In Figures 39 and 40 I show means for automatically and periodically raising the wheel B to compensate for wear of the abrasive material. This means comprises a ratchet wheel l5 secured to the shaft 52 and designed to be rotated by a pawl device ll having an actuating rod 1| mounted to slide in brackets 12 secured to the frame of the machine. Rod 'H is normally held in raised position by a spring 12 and is adapted to be periodically depressed by a. lug 13 carried by a slowly rotating part 242 of the grinding machine. The particular construction of the part 242 and the manner in which it is rotated will be described more fully hereafter. Depres sion of the rod H by the lug 13 serves to rotate the ratchet wheel ill a fraction of a revolution and in this manner slowly raises the grinding wheel B. Connecting link 13' between lug l3 and rod H is preferably pivoted so that it can be swung out of the way when it is desired to discontinue the automatic adjustment of wheel B.

Power for driving the various parts of the machine is derived from an electric motor 15 on the shaft of which is a pinion 16 which drives a gear 18 mounted at one end of a shaft 19 shown in Figures 2 and 10. Shaft 19 is mounted in suitable bearings, as shown, and extends beneath the machine to a change speed gearing, shown conveniently at 80, which drives the turn table J and pick-up mechanism T, as will be described more particularly hereafter. Keyed to the shaft 19, intermediate its length, is a beveled gear 84 which meshes with a gear 85 mounted on a vertical shaft 85, shown at the left of Figure 4.

Rigidly secured to the beveled gear 85 is a gear 99 which drives a gear 9| secured at the bottom of the drive-shaft C.

It will thus be seen that the main grinding wheel B is driven from the motor 15 through pinion l6 gear 18 shaft 19 beveled gears 84 and gear 9!! gear 9| and shaft C.

The motor l5 may, if desired, be provided with suitable controlling means for changing its speed.

The frame of the machine comprises pedestals 69 carrying brackets 11 and terminating in supporting columns 92 connected at their upper ends by a channel bar 93, (see, particularly, Figure 2). The channel bar is formed, or has secured thereto, between its ends, a downwardly inclined guideway 93' having a dove-tailed channel 93" in which is slidably and adjustably mounted the bearing supporting member 94 for the shaft H of the grinding Wheel F. The shaft I-I extends vertically through the member 95 and is journaled in ball bearings 54' in the member 94.

The inner wall of the channel 93 is formed with elongated slots through which project bolts 95 secured to the member 94. By loosening the bolts 95 the wheel F may be adjusted toward or away from the grinding wheel. Adjusting movement of the wheel F is preferably accomplished by a hand-wheel 96 secured to a shaft 95 screw threaded into the top of guideway structure 93. The bearing supporting member 94 is formed with a bracket 94" which surrounds, and is seated in a groove, in, the shaft 96 so that when the shaft 96' is screwed into or out of the structure 93 the bearing supporting structure 94 is moved down or up along the dove tail channel 93.

As may be seen from Figure 13, the grinding wheel F has a relatively narrow annular grinding surface G and from Figure 2 it will be seen that adjustment of the wheel F away from the wheel B has the effect of moving the wheel F toward the center of the wheel B. This is to insure a correct positioning of the wheel F for disks of different diameters. For example, by reference to Figure 13 it will be seen that with the disk holder in the position shown but with a larger disk held by the holder, an adjustment of wheel F upwardly and also away from the disk holder is necessary, in order that the upper edge of the disk will be out off by the correct amount, and in order that this upper edge will engage approximately the same part of the grinding surface of wheel F.

Shaft H, which carries the wheel F, has secured thereto, near its upper end, a pulley 98 adapted to be engaged by a belt 99 driven from a suitable source of power, such as the motor 15 by any suitable transmission, not shown.

The turn table, disk holder assemblies, adjustme'nt and drives The change speed gearing 88 may be of any conventional type and serves to drive at the desired speed a horizontal shaft I08, which, as shown in Figures 2 and 10, is located directly above the main driving shaft 19. Secured to the inner end of shaft I80 is a Worm I 8| which meshes with and drives a worm wheel I82 mounted on-a vertical shaft I83. Shaft I03 carries two gear wheels, a beveled gear I84 mounted at the bottom of the shaft which serves to drive a horizontal shaft I88 which, in turn, drives the pick-up device, (see, particularly, Figure 10), and a second gear I I8 secured to the upper end of the shaft I63 and meshing with an internal gear I I 2 rigid with the turn table J, (see, particularly, Figure 12).

As shownin Figure 4, the gear I I2 is in the form of a ring bolted to the lower face of a portion H5 projecting outwardly from the hub portion H6 of the turn table J.

In practice, the turn table rotates in the same direction as the grinding wheel B, as indicated, for example, by the arrows in Figure 5, but at a very much slower speed. Inasmuch as one complete rotation of the turn table carries the disk through the entire cycle of grinding and finish-

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