US2299850A

US2299850A - Edging machine

Info

Publication number: US2299850A
Application number: US309432A
Authority: US
Inventors: Conrad B Schafer; Oberstar Edward
Original assignee: Libbey Owens Ford Glass Co
Current assignee: Libbey Owens Ford Glass Co
Priority date: 1939-12-15
Filing date: 1939-12-15
Publication date: 1942-10-27
Anticipated expiration: 1959-10-27

Description

oct. 2 7, 1942. c. B. SQHFERETAL 2,299,850

EDGING MACHINE 3 Sheets-Sheet l Filed ne'o. 15, 1939 (Ittorneg Oct. 27, 1942. :,IC, B; ,SCHAFERTAL 2,299,850

EDGING MACHINE Filed Dec. 15, 1939 5 sheets-sheet 2 ww OW @ha hv 4 Ot. 27, 1942. B. scHAr-ER ETAL EDGING MACFHINEl Filed Dec. l5, 1939 3 Sheets-Shed. 3

Gttorneg Puente'd'oct. 21, 1942 EDGING MACHINE ConradB. Schafer, Toledo, Ohio, and Edward Oberstar, Ottawa, Ill., assignors to Libbey-V Owens-Ford Glass Company, Toledo, Ohio, a

corporation of Ohio 'Application December 15, 1939, Serial No. 309,432

(Cl. 5l"74) 20 Claims.

The present invention relates broadly to sur- I, :facing machines and, .more particularly, to a ma- 1 chine `for grinding and/or polishing the edges of l sheets or 'plates of glass and the like. x 4Grenerally speaking, this invention contemplates the provision of an edging machine having a substantially horizontal runway upon which one or .a plurality of sheets or plates of glass or the like ,are supported Ion edge in a lvertical position and along which are adapted to be moved beneath `one or a series of grinding and/ or polishing Wheels to surface the upper edges of said sheets-or plates. Although the invention will be hereinafter Aspecifically described in connection with thelgrinding operation, it will be understood that it may be used equally well for polishing by simply substituting polishing Wheels for the grinding twheels.

Itv is an aim vof this invention to provide an edging 4rd'acltline of the above general character of novela-nd iinproved construction and arrangement and which, While primarily designed for the grinding of curved edges of different contour, is also adapted i-for grinding straight edges or a combination of both.

Another .object ci the invention .is the provision of an'edging machine of the above character embodytngone or more grinding wheels mounted for ,free vertical floating movement so that they can freely follow the `contour of the upper `edges of the glasssheets or plates as the said sheets or plates are passed therebeneath.

v.Another:object of the invention is the provision Cif an vedging machine of the above character hav- "ing means for varying the pressure exerted by the grinding wheel Vupon the upper edges of the glass sheets or plates as `they reach predetermined posi-tions during the grinding'operation 'whereby to obtain maximum grinding eiliciency. ,A .iurther object of the invention is the provi- :sion lof a'necing :machine lof Vthe above character having means :for maintaining the glass sheets or plates in proper vertical position as they are earrlcd lforwardly beneath the `grinding Wheel and f `for holding them in `:such a manner that f vibration of the said sheets or pla-tes and any i breakage incident thereto is reduced to a mini- Astill `further object of the invention is the provision o; an edging machine of the above characteiiwhich is of relatively Isimple inexpensive construction, easy to assemble and adjust, positive vand rapid in action, eiiicient and durable in service. and a `general improvement in the art.

other objects and advantages of the .invention will become `more apparent during the course of the following description, when taken in connection with the accompanying drawings.

In the drawings,` wherein like numerals are employed to designate like parts throughout the same:

Fig. 1 is a side elevation of an edging machine constructed in accordance with the invention;

Fig. 2 is a horizontal longitudinal section taken substantially on line 2--2 of Fig. 1;

Fig. 3 is a plan View of the grinding wheel and one of Athe hold-down units for the glass sheets or plates being ground;

lig. 4 shows an .alternate type of grinding Wheel; I I

Fig. 5 is a detail section taken substantially on line 5`5 of Fig. 1 I

Fig. `6 is an elevation of one of the dash-pots used in the machine, partially broken away; and

Fig. -'l is a diagrammatic view illustratingvthe operation of the machine.

With reference now to the drawings, the machi-ne comprises in general the means A for supporting the glass sheets Il] to be ground on edge in a vertical position and which sheets are adapted lto -`:be vpassed alongsaid supporting means beneath" the grinding mechanism B including `a rotatable grinding wheel I I. g

The means A for supporting the glass sheets `Ill 'comprises a substantially horizontal runway including the spaced parallel longitudinally eX- tending side boards I2 and I3 carrying therebetween a series of horizontally aligned freely rotatable conveyor rolls I4 leading to the grinding wheel I I and a series of similar conveyor rolls I5 leading away from said wheel. The conveyor rolls I4 and I5 are `adapted to support the glass sheets to be ground on edge in a vertical position and are 4preferably provided with grooves I6 for receiving the lower edges'o-f the said sheets therein; The conveyor rolls Ilserve-to convey the glass sheets to the grinding wheel II, while the conveyor rolls I5 receive the sheets as they pass from said Wheel land convey them either to a `second grinding wheel, a polishing wheel or any suitable point.

The glass sheets I0 are adapted to'be moved continuously forwardly along the supporting runway and beneath the grinding wheel II. Any `suitable means may be provided for propelling the glass sheets forwardly, `and the means herein shown by Way of example comprises a pusher block I1 engaging the rear edges of the glass sheets. This pusher block is carried by a sprocket `chain `I8 which slides along upon the Upper edge of one of the side boards I2 or I3 of the sheet supporting runway.

The grinding wheel I i is mounted upon a horizontal shaft I9 journaled at its opposite ends in bearings 213 and 2I `which are carried at one end of a relatively long, substantially horizontal supporting arm 22. The supporting arm 22 is pivotally mounted adjacent its opposite end upon a horizontal shaft 23 supported at its opposite ends in bearings 24 and 25 carried by vertical channel beams 26 and 2'I respectively. Each bearing 24 and 25 is carried by a bracket 28 having ,a base ange 29 secured to the respective channel beam 26 or 2'I by bolts or the like 3i). Y

The supporting arm 22 isprovided with spaced bearing blocks 3| and 32 through which the shaft 23 extends and upon which said supporting arm is rockably mounted. Carried upon the shaft 23 between the bearing blocks 3l and 32 is a collar 33 secured to said shaft by a screw or the like 34. The provision of the collar 33 prevents the supporting arm 22 from shifting laterally upon the shaft 23. The fastening bolts 38 for brackets 28 pass through vertical slots in the base flanges 29 so that the said brackets can be adjusted vertically to raise or lower the supporting arm 22 and grinding wheel II. To effect this adjustment of the brackets 28, there is secured to each channel beam 23 and 21 an angle plate 35 (Fig. l) through which is threaded a vertical screw 33 having its upper'end engaging the respective bearing 24 or 25. Byfirst loosening the bolts 3B and then adjusting screws 36, the brackets 28 can be moved vertically to raise or lower the supporting arm and grinding wheel.

Mounted upon the supporting arm 22 at the end thereof remote from the grinding wheel II, is a motor 3l for driving the said wheel. The driving of the grinding wheel is effected by means of an endless belt 38 trained about a pulley 39 keyed to the shaft of motor 31 and also about a pulley 40 fixed to one end of the grinding wheel shaft I9. The drive belt 38 and pulleys 39 and 40 may be enclosed in a housing 4I if desired.

The grinding wheel Il maybeprovided with a plain or flat grinding surface, as shown in Fig. 3, or it may be provided with a plurality of peripheral grooves 42 as illustrated in Fig..4 for receiving the curved upper edges a of the glass sheets I3 therein to effect a rounding of said edges.

In thev operation of the machine, the glass sheets I6 are initially supported on edge upon the conveyor rolls I4 and moved forwardly thereover to and beneath the grinding wheel I I.I When in normal inoperative position, the grinding wheel assumes the position shown in Fig. 1 where it is disposed in the path of travel of the glass sheets I3. As the forward edges of the glass sheets engage the grinding wheel, they act to move the said wheel upwardly by rocking the supporting arm 22 upon shaft 23. However, since the grinding wheel is mounted for free vertical floating movement and normally urged downwardly by its own weight into engagement with the sheets I9 it is free to follow the upper edges a' of the said sheets regardless of the curvature thereof.

The present invention also contemplates the provision of novel means for effectively maintaining the glass sheets II! in proper vertical position and against vibration during the grinding operation whereby to facilitate an even uniform grinding of the sheet edges as well'as reducing the liability of breakage of the glass to a minimum. Such means comprises a plurality of holddown units 93, 36, and 45 mounted beneath the path of travel of the glass sheets and so spaced from one another that the sheets are engaged by at least two of the units during the grinding thereof.

Each of the hold-down units (I3, 13, and 45 comprises a pairef inclined arms'i and 41 disposed at opposite sides of the sheet sup-porting runway and pivoted at their lower ends upon horizontal trunnions 38 and formed upon brackets 50 and 5I carried by the side boards I2 and I3 respectively of said runway. The inclined arms 36 and Ill' are connected together at their upper ends by a horizontal substantially U- shaped strap 52 carrying a hold-down roller 53 adapted to engage the upper edges of the glass sheets. The roller 53 is preferably provided with grooves 54 for receiving the upper edges of the glass sheets therein. Also mounted upon the horizontal trunnions 58 and i3 outwardly of 'and secured to the inclined arms v136 and filare the depending legs 55 and 55 respectively -having cylindrical end portions 5l, and 58 upon whichare slidably mounted the weights 59 and 33. The depending legs 55 and 5t extend at substantially right angles to the inclined 'arms i5 and il and cooperate therewith to form bell-cranklevers which are normally urged in a clockwise direction upon the trunnions t3 and i3 by the weights 53 and 63 so as to force the roller 53 downwardlyl into engagement with the upper edges of the glass sheets. By proper adjustment of the weights 59 and E3, the pressure-of the roller 53 upon the sheet edges can be varied as desired.

To assist in maintaining the hold-down rollers 53 in rm engagement with the upper edges lof the glass sheets as the said sheets passy theres beneath, there is associated with leach holddown unit L13, 44, and [a5 a dash-pot 6I which may be of the construction illustrated in Fig. 6. The dash-pot El comprises an elongated cylindrical casing closed at its opposite ends and p-ivoted at its lower end as at 62 to a yfixed bracket 63 (Fig. 1). Slidably mounted within the casing isf'qa piston rod B4 carrying at its lower end a-piston 55 which snugly engages the wall of said casing: The piston S5 is provided with a plurality of openings 66 extending vertically therethrough and secured upon the upper surface of the piston is a flexible disk 6l.

When the piston '65 is moved upwardlywithin the casing, the flexible disk 6l will assume'the position shown in full vlines in Fig. 6 and thus act to close the openings 66. Consequently, upon up; ward movement of the piston E55 the-liquidfcon'- tained within the casing above said piston can;- not pass through the openings 63 and is there'- fore by-passed around the piston into th'eiower end of the casing through the pipes 38, 69, and-"lil, On the other hand, when the piston 55E-moves downwardly, the marginal edge portion onthe flexible disk 3l will be forced upwardly into broken line position so that the liquid'- beneath the piston can flow through thel openings 56'. A valve 1I is preferably interposed in the pipef'ES to control the flow of the liquid therethrough; The piston rod @Il extends through the upper-'end of the casing and is internally threaded" to receive therein one end of a threaded rod 12'(F'g'. 1) which is in turn threaded at its upper' endin al block 'i3 pivoted as at 'Il to one of the inclined arms 46 or Il intermediate the ends thereof.

When the glass sheets Il aremove'd forwardly along the supporting-runway,'the-rollers: E539 of the hold-down units 4.3, 44., and .Il :are Asuccessively engaged by the upper .edges Ia of the sheets, and as .the `said .sheets `pass tbeneath l.auch roller,

the said roller is moved upwardly `therebw due to. f

the swinging of the arms 46 and 4l jupon trunnions 48 and 49. The weights il and i wiilof course serve to holdy the roller 53 down in .en-- gagement with the sheet edges. Upon 'upward movement of the roller 5.3., the respective lpiston rod 64 will also be drawn `ixprmrdly to effect upward movement Lof the piston .55..` will result `in the flexible disk 51 dlattened out. as shown in full lines inF'ig. 6, to close V'the :openings 66 and thus prevent the liquid yfrom passing through said openings from the upper end of the casing into the lower lend iii-hereof. 'fSince the liquid cannot `pass through the openings 6.6 yit will flow lthrough pipes 618 '59.. and ill into the lower end of the casing. By proper regulation of the valve 1I, the `flow of liquid through-,the pipe 69 can be so controlled that it will :oder a predetermined resistance to the upward -mcvement of the roller 53 whereby said :roller will exert a rm, steady downward pressure upon the upper edges of the glass sheets to hold :them in proper Vertical position, `as well as `mirrh'nize `vl- 1 bration thereof during grinding. Qn the other hand, when the glass sheets pass `beyond the roller 53, the roller is `permitted to drop quite rapidly to normal inoperative position. This is due to the fact that, as the .roller :moves downwardly to also effect downward movement ofthe piston 65, the disk 61 will assume .the broken line position inv Fig. .6, .so Athat the liquid can `:pass upwardly through the openings 66,. Although it is preferred to make use Aof a dash-pot .arrangement as above described, other means may be employed to retard the .upward movement ofthe roller 53, such as a check valve or lthe like.

As the glass sheets I move orwardlyalong the supporting runway, they will .engage the grinding wheel II and, due to its pivotal mounting, the said wheel will be moved upwardly `by the 4sheets and caused to follow the contour 4of the upper edges thereof as the sheets pass beneath said wheel. After the sheets pass beyond the grinding wheel, it is adapted to drop downwardly by `its own weight to normal inoperative position. For the purpose of 4retarding the downward movement of the grinding wheel to prevent .it from dropping too rapidly, there is provided -a dash-pot similar 'to the dash-pots BI of the lhold-down

units

43, 44, and 45.

The dash-pot 15 is pivoted at its lower end .to the supporting arm '22 as at 16 while the A.piston rod 11 thereof has threaded in its outer end .a rod 18 carried by a block '19. 'The block I9 has In order to obtain an even and uniform grinding 'of the upper :curved edges a of the glass sheets, it is necessary that thepressure exerted by the grinding wheel upon the sheet edges be varied as the sheets pass beneath said wheel. Referring particularly to Fig. '7., as the glass sheets I0 pass beneath grinding wheel II and the said wheel travels along the curved edges a from point b to point c, the only pressure required to be exerted upon the sheets is the weight of the grinding wheel and its associated parts. However, as the grinding wheel passes ufrom point `c to point d, it is necessary that the pressure exerted thereby upon the sheet edges be increased, while .from point d to point e the pressure `can again be decreased to the weight of the grinding Wheel and its associated parts. In other words, as the curve of the sheet edges flattens out, such as from point a to point d, it is necessary that the grinding pressure be increased. Although it is to `beexpressly understood that the invention is not limited to the use of any specic pressures (as this depends upon the curvature of A the .sheet edges), it has been found that, when grinding glass sheets having their upper edges curved in the manner illustrated in Fig. '1, it is preferred that the grinding wheel exert approximately twenty-five pounds pressure upon the sheets as said wheel passes from point b to point c, approximately sixty to seventy pounds pressure in passing from point c to point d, and approximately twenty-five pounds pressure from point d to point e.

. In vaccordance with the invention, the pressure exerted by the grinding `wheel I I upon the upper edges of the glass sheets is adapted to be automatica'lly'varied as the sheets pass therebeneath in the following manner. Secured to the supporting arm 22 is a bracket 83 having a relatively long slot 84 therein. Slidably received within the slot 84 is a horizontal pin 85 carried at the lower end vof a substantially vertical bar 86, the upper end of which is operatively associated with an electromagnetic holding unit designated in its entirety by the numeral 81. Secured to the bar 8'6, adjacent the lower end thereof, is a substantially horizontal platform 88, while suspended above the platform is a weightV 89. This weight consists preferably of a disk carried at the lower ends of cables 98 and having an open slot 9i therein for receiving the bar 86. As the grinding wheel II is forced upwardly -by the glass loosely received within a vertical .slot Il and in a fixed plate 82. The dash-,pot 15 is vpreferably of the same construction as the dash-pot Il abovedescribed, with the exception that 'the flexible disk 61 thereof is secured to the Tbottom of ,the piston 65 rather than to the top thereof as shown in Fig. 6. This arrangement will not retard the upward .movement ofthe grinding wheel but will serve to prevent a too sudden dropping of the wheel after the glass sheets pass therebeyond. That is to say, the liquid within the dash-pot will he permitted to flow through `the openings 66 in the piston 65 upon upward movement of the grinding wheel whereas when the said wheel moves downwardly the openings will be closed by the iiexible disk 51 andthe liquid 'bypassed through the pipes '68, Il, Iand 1l.

sheets moving therebeneath, the supporting arm 22 will be rocked upon shaft 23 in a clockwise direction to also move the bar 86 upwardly. Upon upward movement of said bar, the platform 88 will engage and lift the disk 89 and, obviously, when `the disk 89 is supported upon the platform 88 the pressure exerted by the grinding wheel upon the sheet edges will be increased according to the weight of said disk.

In practice, the disk 89 is `adapted to be lifted l by the platform 88 when the grinding wheel II jrs reaches the point c as shown in full lines in Fig. 7, so that during the travel of the wheel from point c to point d the added weight of the disk 89 will be applied to the edges of the glass sheets. On the other hand, when the grinding wheel reaches point d and begins to move downwardly to point e the pressure is adapted to be again decreased as described above. This is accomplished by permitting the grinding Wheel I I to move downwardly 'by its own weight while at the same time maintaining the bar 86 and disk 89 in elevated position by operation of the holding unit 81.

Ihis unit comprises a horizontal, substantially U-shaped bracket 92 arranged between a pair of spaced vertical hangers 93 and 94 and provided with trunmons $5 and Q which are received Within openings in said hangers 93 and 9e respectively. Carried by the bracket E2 is a solenoid 97 having a plunger S8 to which is pivoted as at 99 one end of a bolt |00 upon which is threaded a nut lill. The bracket 92 is provided with a head H32 formed with a rectangular groove or recess m3 in which the bar 8S is sldably received. The head H32 of bracket 92 is also provided with spaced ears IM and H35 (Fig. 1) between which is received a clamping block |05 pivoted to said ears at one end as at Iil and having an open slot it in its opposite end for receiving the bolt H59. rlhe clamping block l 06 is further provided at one side with a notch IDS and disposed in said notch is a pin ll upon which is pivoted a clamping plate HI having a vertically disposed ange H2 eX- tending parallel with bar 86 and having its outer face covered with a strip of rubber, rubber composition or the like H3. Upon energization of the solenoid 97, the plunger 98 thereof is adapted to be drawn inwardly to swing the clamping block 506 upon its pivot I'l to cause the bar 3S to be rmly clamped against movement within the recess 103 by means of the iiange H2 on clamping plate IH. Upon deenergization of the solenoid,

however, the clamping block it is forced outt wardly by a spring IM to release the clamping vaction upon the bar 86. v l

During the grinding operation,V and as the grinding wheel Il passes along the sheet edges from point b to point d, the solenoid 521v is adapted to be deenergized so that the bar 36 can move 'upwardly within the recess 93 upon raising of the grinding wheel. However, when the grinding wheel reaches point d, and begins its downward movement, the solenoid is adapted to be automatically energized to maintain the bar 86 and disk 89 in elevated position, while permitting the grinding wheel to move downwardly by its own weight. To this end, a limit switch I l5 is secured to the sheet supporting runway and connected in series with the solenoid, said switch having a pivoted lever .arm l i6 carrying at its outer end a roller H1. When the glass sheets move beneath the grinding wheel and the said wheel reaches the point d on the sheet edges, the pusher block Il for the sheets is adapted to engage roller i lll and force lever. arm H6 downwardly to close the switch H5. lThe closing of the switch will eifect the energizing of the solenoid 91 and the clamping of the bar 86 in raised position. Due to the relatively long slot 8d in bracket 83, the grinding wheel can then move downwardlyas it passes from point d to point e while the weight 89 is held in raised position along withthe bar 85, When the pusher block l1 passes beyond limit switch H5, the switch will be automatically opened to deenergize the solenoid and thereby release the bar and weight so that they can move downwardly to initial position. By the time the switch is opened, the glass sheets will have passed beyond the grinding wheel.

It will of course be appreciated that one or anyl desired number of grinding wheels l l may be'employed and 4also that one or a plurality of polishing wheels can be arranged in line therewith, if preferred. Further, the machine may be used for the edging of sheets or plates of other material and is not restricted to use in the surfacing of glass sheets.- y

It is to be understood that the form of tht-finaly venticn herewith `shown and described is to be taken as the preferred. embodiment of the same, and that-various :changes in the shape, size and arrangement of partsfmay be resorted to without departing from the spirit of the invention or the sccpeofzt-he subj oined claims.

1` In apparatus vfor grinding the edges of sheets or plates of 'glass' and the like, means for supporting the sheeton-'edge `in a vertical position and for.l carrying'ithensame-forwardly in a generally horizontal direction, means mounted above the path of trave-l ofthe sheet for grinding the upper edge vof said sheet during forward movement thereof, means for mounting said grinding means for free'vertical'movement so that it can freely follow the kcontour of the upper edge of the sheet, the weight ofi the grinding means exerting an initial pressure upon '-.the upper edge of the sheet, and separate pressure means normally ineffective and rendered eiiective byupward movement of the grinding 'ineans for applying increased pressure to said grinding means to -urge it downwardly into? engagement with the upper edge of saidsheet.

2. 'In apparatus for grinding the edges of sheets er plates -of glass and the like, means for supporting the' 'sheet-'on edge in a vertical position and for carrying the 'same forwardly in a generally horizontal direction, means mounted above the path of :travel of the sheet for grinding the upper edge ofs'aid sheet during forward movement thereof, means' 'for mounting said grinding means for lfree'v'ertical movement so that it can freely follow "the contour of the upper edge of the sheet, and 'weightadapted to be automatically applied toI th''grinding means upon upward movement thereof to urge said grinding means downwardly with increased pressure into engagement with the upper edge of said sheet.

I In' apparatus for grinding the edges of sheets or platesoffglass and the like, means for supporting the'fs'h'eet onedge in a vertical position and for carrying the same forwardly in a generally horizontaldirectiom la grinding wheel beneath-'whichfthef sheet is adapted to be moved, a supporting Aarm carrying said grinding wheel at onel end' ndpivotally mounted adjacent its opposite' en motor' carried by said supporting `arm fordrivinglsaid grinding wheel, said grinding wheel'being adapted to freely follow the contour ofthe upper edge of the sheet as said sheet moves therebeneath, and pressure means independent Vofr said supporting arm mounted in tion" thereabove and adapted to be hesaid 4supporting arm upon upentlthereof to urge said grinding wheel fd :ardly with increased pressure into engagernen vvvitnfth-e upp'eredge of said sheet. v 4'. I ,n apparatus for grinding the edges of sheets orpl'ates 'cf 'glass'and the like, means for supporting the sheet on edge'in a vertical position and carrying` the' same forwardly in a generallyhorizpntal direction, a grinding wheel beneath which theslieet is adapted toibe moved, afsupporti a'rrri "carrying said grinding wheel at one'en, vandpivotally mounted adjacent its opposite end, a motor carried by said supporting arm forl 'ivirg'said grinding wheel, said grinddapted'to freely follow the conrate pressure means independent of said supporting -arm mounted in spaced relation thereabove and adapted to be engaged bythe said supporting arm upon upwardmovement thereof to urge said grinding wheel downwardly with increased pressure into engagement with the upper edge of saidl sheet.

`5. In apparatus for grinding the edges of sheets or plates of glass and the like, meansA for supporting the sheet on edge in a vertical position and for carrying the same forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adapted to be moved, a supporting arm carrying `said grinding wheel at oneend and pivotally mounted adjacent its opposite end, a motor `carried by said supporting arm for driving saidgrinding wheel, said grinding wheel being adapted to freely follow the contour of the upper edge of the sheet a's said sheet moves therebeneath, and a weight adapted to be'picked up by said supporting arm upon upward movement of the grinding wheel to urge said grinding wheel downwardly with increased pressure into engagement with the upper edge of said sheet.

GQ `In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet onedge in a vertical position and for carrying the same forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adapted to be moved, a supporting arm"carrying said grinding wheel at` one end and pivotally mounted adjacent its opposite end, a motor carried by said supporting arm for driving said grinding Wheel, said grinding wheel being adapted to freely follow the oontour of the upper edge of the sheet as said sheet moves therebeneath, a weight adapted to be pickedupl by said supporting arm upon upward movement of the grinding wheel to urge said` grinding wheel downwardly with increased pressure into engagement with the upper edge of said sheet, and means actuated when the sheet reaches a ,predetermined position beneath thel 1 grinding wheel forholding said weight in elev ated position while said grinding wheel moves downwardly as said sheet passes therebeyond,

'7. In apparatusfor grinding the edges of sheets or plates of glass and the like, means` for supporting the sheet on edge in a vertical position` lio' and for carrying the same forwardly in a generally horizontal direction, a grinding wheel `beneathwhich the sheet is adapted to be moved, a vsupporting arm carrying said grinding wheel at one end and pivotally mounted adjacent its opposite end, a motor carried by said supporting arm for driving said grinding wheel, said grinding wheel being adapted to freely follow the contourof the upper edge of the sheet as said sheet movesgtherebeneath, ay weight adapted` to be pickedup by said supporting arm upon upward movement of the grinding wheel to urge said grinding wheel downwardly with increased pressureinto engagement with the upper edge of said. sheet; means actuated when the sheet reaches a` predetermined position beneath the grinding wheels. for holding said weight in elevated posi-` tion while said grinding wheel moves downwardly assaid sheet passes therebeyond, and means for' retarding the downward movement of the said grinding wheel.`

8F. 'In apparatusfor grinding theedges of. sheets or plates of glass and the like, means for. supporolng the ,sheet on edge in a vertical position and for carrying the same forwardly in a generally horizontal direction, a grinding wheel beneath `which the sheet is adapted to be moved, a supporting arm carrying said grinding wheel at one end and pivotally mounted adjacent its opposite end, a motor carried by said supporting armfor driving said grinding wheel, said grinding wheel being adapted to freely follow the contour of theY upper edge of the sheet as said sheet moves therebeneath, a weight adapted to be picked up-by said supporting arm upon upward movement of the grinding wheel Vtourge said grinding wheel downwardly with increased pressure into engagement with the upper edge of said sheet,` means for propelling the sheet forwardly beneath the grind-ing wheel, and means actuated by said propelling means when the sheet reaches aV predetermined position beneath said grinding wheel for holding said weight in elevated position while said grinding wheel moves downwardly as said sheet passes therebeyond.

9. n apparatus for grinding the edges of sheets or platesof `glass and the like, means for supporting the sheet on edge in 'a vertical position l. and for carrying the same forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adaptedto be moved, a supporting arm carrying said grinding wheel at one end and pivotally mounted adjacent its opposite end, a motor carried by said supporting arm for driving said grinding wheel, said grinding wheel being adapted' to freely follow the contour of the upper edge of the sheet as said sheet moves therebeneath, a weight adapted to be picked up by said supporting arm upon upward movement of the grinding wheel to urge said grinding wheel downwardly with increased pressure into engagement with thel upper edge of said sheet, means; for propelling the sheet forwardly beneath the grinding wheel, means actuated by saidv propelling ymeans when the sheet reaches a predetermined position beneath said grinding wheel for holding said weight in elevated position while said grinding wheel moves downwardly as said sheet passes therebeyond, and means for retarding the downward movement of the said grinding wheel;

t 10.- In apparatusy for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for carrying thel same forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adapted to be moved, a supporting arm carrying' said grinding wheel at one end and pivotally mounted adjacent its opposite` erlid,A a motor carried by said supporting arm for driving said grinding wheel, said grind-l ingwheel being adapted to freely follow the contour of the upper edge of the sheet as said sheet moves therebeneath, 4a weight suspended above the supporting arm,i a substantially vertical ba-r pivotally connected at its lower end to said supporting arm and having means for picking up said Weight upon upwaivdv movement of the grindilng wheel to urge Said grinding wheel downwardly withincreased pressure into engagement with theD upper edge ofthe sheet, and means for holding said bar and weight in elevated position while said grinding wheel moves downwardly as said Sheet passes therebeyond.

lil..` In'- apparatusl for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in averti'cal position and for carrying! the same forwardly in a generally horizontal direction, a;V grinding wheel be-v neath which the sheet is adapted to be moved, a supporting arm carrying said grinding wheel at one end and pivotally mounted adjacent its opposite end, a motor carried by saidsupporting arm for driving said grinding wheel, said grinding wheel being adapted to freely follow the contour of the upper edge of the sheet as said sheet moves therebeneath, a weight suspended above the supporting arm, a substantially vertical bar pivotally connected at its lower end to said supporting arm and having means for picking up said weight upon upward movement of the grinding wheel to urge said grinding wheel downwardly with increased pressure into engagement with the upper edge of the sheet, and electromagnetic means operable when the sheet reaches a predetermined position beneath said grinding wheel to hold said bar and weight in elevated position while said grinding wheel moves downwardly as said sheet passes therebeyond.

l2. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for carrying thel same forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adapted'to be moved, a supporting arm carrying said grinding wheel at one end and .pivotally mounted adjacent its Cil opposite end, a motor carried by said supports ing arm for driving said grinding wheel, said grinding wheel being adapted to freely follow the contour of the upper edge of the Ysheet as said sheet moves therebeneath, a weight suspended above the supporting arm, a substantially vertical bar pivotally connected at its lower end to said supporting arm and havingmeans for picking up said weight upon upward movement of the grinding wheel to urge said grinding wheel downwardly with increased pressure into engagement with the upper edge of the sheet, electromagnetic means operable when the sheet reaches a predetermined positionbeneath said grinding wheel to hold said bar and weight in elevated position while said grinding wheel movesY downwardly as said'sheetpasses therebeyond, and means for automatically rendering said electromagnetic means inoperative when the sheet passes beyond said grinding wheel to cause the lowering of the said bar and weight. 'Y

13. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for varrying the same `forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adapted tobe moved, a supporting arm carrying said grinding wheel at one end and pivotally mounted adjacent its opposite end, a motor carried bysaidsupporting arm for driving said grinding wheel, said grinding wheel being adapted to freely follow the contour of the upper edge of the sheet as said sheet moves therebeneath, 4a weightA suspended above the supporting arm, a substantially Vertical bar pivotally connected at its lower end to said supporting arm and having means for picking up said weight upon upward movement of the grinding wheel to vurge said grinding wheel downwardly with increased pressure into engagement with the upper edge ofthe sheet, means for propelling the sheet forwardly beneath the grinding wheel, electromagnetic means associated with said bar, and means operable by said propelling meanswhen the sheet reaches a predetermined position beneath said grinding wheel forl energizing said electromagnetic means tovhold said bar and weight in elevated position while the said grinding wheel moves downwardly as said sheet passes therebeyond.

14. In apparatus for grinding the edges or sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical posi,-4 tion and for carrying the same forwardly in a. generally horizontal direction, a grinding wheel beneath which the sheet is adapted to be moved, a supporting arm carrying said grinding wheel at one end and pivotally mounted adjacent its opposite end, a motor carried by said supporting arm for driving said grinding wheel, said grinding wheel being adapted to freely follow the contour of the upper edge of the sheet as said sheet moves therebeneath, a weight suspended above the supporting arm, a substantially vertical bar pivotally connected at its lower end to said supporting arm and having means for picking up said weight upon upward movement of the grinding wheel to urge said grinding wheel downwardly with increased pressure into erigagement with the upper edge of the sheet, means for propelling the sheet forwardly beneath the grinding wheel, electromagnetic means associated with said bar, a limit switch adapted to be closed by said propelling means when the sheet reaches a predetermined position beneath said grinding wheel for energizing said electromagnetic means to hold said bar and weight in elevated position while said grinding wheel moves downwardly as said sheet passes therei beyond, said limit switch being automatically opened as said propelling means passes out of engagement therewith to deenergize said electromagnetic means and cause the lowering of the said bar and weight.

15. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for carrying the same forwardly in a generally horizontal direction, means for holding the sheet in proper vertical position during l grinding comprising a pair of inclined arms arranged at opposite sides of the path of travel of the sheet and pivotally mounted at their lower ends beneath the path of travel of said sheet, a

, hold-down roller carried between said arms at their upper ends and engaging the upper edge of the sheet, and means for urging said arms about their pivots to hold said roller down in engagement with the sheet edge.

16. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for carrying the same forwardly Y in a generally horizontal direction, means for holding the sheet in proper vertical position during grinding comprising a pair of inclined arms arranged at opposite sides of the path of travel of the sheet and pivotally mounted at their lower ends beneath the path of travel of t said sheet, a hold-down roller carried between said arms at their upper ends and engaging the upper edge of the sheet, means for urgingsaid arms about their pivots to hold said roller down in engagement with the sheet edge, and means for retarding the upward movement ofthe said roller during travel of the sheet therebeneath to hold it in firm engagement with the edge of said sheet.

17. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edgein a vertical position and for carrying the same' forwardly in a generalaeeasso down roller carried between said arms at their upper ends and engaging the upper edge of the sheet, a pair of legs secured to the lower ends of said arms and extending at substantially right angles thereto, and weights carried by said legs for rocking the said arms about their pivots to hold said roller down in engagement with the sheetl edge.

18. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for carrying the same forwardly in a generallyhorizontal direction, means for holding the sheet in proper vertical position during grinding comprising a pair of inclined arms arranged at opposite sides of the path of travel of the sheet and pivotally mounted at their lower ends beneath the path of travel of said sheet, a holddown roller carried between said arms at their upper ends and engaging the upper edge of the sheet, a pair of legs secured to the lower ends of said arms and extending at substantially right angles thereto, weights carried by said legs for rocking the said arms about their pivots to hold said roller down in engagement with the sheet edge, and means connected to the said arms for retarding the upward movement of the said roller during travel of the sheet therebeneath to hold it in firm engagement with the edge of the sheet.

19. In apparatus for grinding the edges of sheets or plates of glass and the like, means for supporting the sheet on edge in a vertical position and for carrying the same forwardly in a generally horizontal direction, means mounted above the path of travel of the sheet for -grinding the upper edge of said sheet during the forward movement thereof, means for mounting said grinding means for free vertical movement so that it can freely follow the contour of the upper edge of the sheet, and separate pressure means independent of said grinding means mounted in spaced relation thereabove, said separate pressure means being normally ineffective and rendered effective by upward movement of said grinding means to urge the said grinding means downwardly with increased pressure into engagement with the upper edge of said sheet.

20. In apparatus for grinding the edges of sheets or plates of glass and the like, meansl for supporting the sheet on edge: in a vertical position and for carrying the same forwardly in a generally horizontal direction, a grinding wheel beneath which the sheet is adapted to be moved, a supporting arm carrying said grinding wheel at one end and p-ivotally mounted adjacent its opposite end, a motor carried by said supporting arm for driving said grinding wheel, said grinding wheel being adapted to freely follow the contour of the upper edge of the sheet as said sheet moves therebeneath, and separate pressure means mounted in spaced relation above the grinding wheel adapted to be picked up by said supporting arm upon upward movement of said grinding wheel to urge the said grinding wheel downwardly with increased pressure into engagement with the upper edge of said sheet.

CONRAD B. SCI-IAJEFR.` EDWARD OBERSTAR.