US1929810A - Glass grinding machine - Google Patents

Description

1933- E. EDWARDS ET AL GLASS GRINDING MACHINE Filed Dec. 26, 1930 3 Sheets-Sheet l fnfierztors:

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GLASS GRINDING MACHINE Filed Dec. 26, 1930 3 Sheets-Sheet 2 lndn 07's Zdzzrard Ida/Q7015;

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Patented Oct. 10, 1933 UNITED STATES PATENT OFFICE GLASS GRINDING MACHINE tion of Illinois Application December 26, 1930 4 Serial No. 504,832

7 Claims. (01. 51-34) The utility, objects and advantages of the present invention will be apparent fromthe accompanying drawings and following detail description.

In the drawings, Fig. 1 is a fragmentary side elevational view of the grinding machine.

Fig. 2 is a fragmentary side elevational view of the opposite side of the device shown in Fig. 1.

Fig. 3 is a plan sectional view taken on the line 33 of Fig. 2.

Fig. 4 is a profile sectional view taken-on the line 4-4 of Fig. 1. I

Fig. 5 is a fragmentary profile view of one grinding wheel in grinding position upon a plurality of plates, shown in section.

Fig. 6 is a detail plan view of means for supporting the plates in spaced relation.

Fig. '7 is a fragmentary detail side elevational view of the guide wheel for each grinding wheel, the full lines illustrating operative or grinding position and the dotted lines indicating inoperative position.

Fig. 8 is a detail sectional view taken on line 88 of Fig. 7.

Fig. 9 is a detail sectional view taken on line 9-9 of Fig. 7.

Fig. 10 is a perspective detail view of one wheel supporting lever shown in assembly in Fig. 2.

Fig. 11 is a similar view of the supporting lever for the other wheel. 7

Fig. 12 is' a fragmentary top plan view of the track for the guide wheels illustrating the lever trips in operative position.

Fig. 13 is a detail side elevational view of the trip for the lever shown in Fig. 10.

Fig. 14 is a detail side elevational view of the trip for the lever shown in Fig. 11.

Fig. 15 is a detail perspective of a section of guide track for grinding a curved edge.

Fig. 16 is a detail side elevational view of a portion of the mechanism for adjustably raising 'or lowering one of the grinding wheels.

Fig. 17 is a sectional view taken on line 16-16 of Fig. 1'7. 3 I

Referring in detail to the drawings, 1 indicates a support which may take the form of an A frame having opposed legs 2 and 3, an upper connecting member 4 and an intermediate connect ing member .5. [The lower endsof legs 2 and 3 within bearing 19 mounted upon frame 1.

ated with said screw by means of the internally may be joined by a base connecting member 6.' The machine proper may be provided with two such frames, one at each end, said frames being connected by tie rods 2' and 3'.

A hollow cylinder '1 may be vertically disposed between the legs 2 and 3 of each of the frames 1 and may be mounted upon the base connecting member 6, the upper ends of said cylinders terminating adjacent the intermediate connecting members 5. A platform 8 may be supported be tween the cylinders '7 and may comprise a pair of longitudinally parallel channels 9 connected at their lower edges by a bottom plate 10 and at their upper edges by a tray-like member 11 which may be provided with an upwardly extending flange 12. The platform 8 is slidably associated at each of its ends with each ofthe cylinders '7, and the arrangement is such that said platform may be adjusted to occupy any desirable position along the length or height of the cylinders 7.

To move said platform upwardly or downwardly, as the casemay be, a rotatable screw 13 may be disposed adjacent and parallel to each of the cylinders 7. Internally threaded members 14 may be mounted upon the side of one of the channels 9 in any suitable manner, the threads of said member being adapted to engage the screw 13. A hand wheel 15 may be suitably journalled with respect to one ofthe end frames 1 and may be rigidly connected to a bevel gear. 16, which in turn may mesh with a cooperating bevel gear 17 mounted upon vertically disposed shaft 18. Said latter shaft may be imm'ovably connected to screw 13 and maybe journalled It can readily be seen that upon manually rotating hand wheel 15 said bevel gears will be rotated, thereby turning shaft 18 and screw 13. Obviously, upon rotation of screw 13 platform 8, associthreaded member 14, will move upwardly or downwardly, depending upon the direction of rotation of the hand wheel 15.

In order that both ends of the platform 8 may move upwardly or downwardly in a uniform man- 1 ner, that is, so that the plane of said platform may be maintained in a truly horizontal position and to prevent binding of the ends of the platform upon the cylinders 7, a screw 13 may be provided at each end of said platform adjacent each of the cylinders 7. The screw remotely posi- 'tioned from hand wheel 15 may be operated in a manner which will be hereinafter more fully described. A bevel gear 20 may be mounted upon the upper end of shaft 18 and may be adapted to engage or mesh with a cooperating bevel gear 21 mounted upon shaft 22. Said shaft may traverse the entire length of the machine proper and may be provided with a suitable complement of bevel gears at its opposite end in order that motion of rotation from the hand wheel 15 maybe imparted to the screw 13 remotely positioned from said hand wheel. In this manner both screws 13 may be rotated synchronously, and consequentlyboth ends of platform 8 will be moved at a uniform rate. To facilitate the movement of said platform the same may be counter-balanced by means of weights 23, which may be adapted to ride upwardly and downwardly within the hollow portions of cylinders 7, said weights being connected by flexible means such as rope or cords 24 to the platform, said flexible means intermediate its length being carried over suitable sheave wheels 25, supported from the upper portion 4 of the frame 1. In this manner said platform may be moved upwardly or downwardly in an accurately controlled manner.

A pair of rails 26 may be longitudinally disposed upon the upper portion of frame 1 and at one end of the machine may extend outwardly from said frame to support a motor 27 and speed reducing device 28. Said motor may be connected by means of belt 29 to the speed reducing device 28, the latter being provided with a plurality of gears 30 of different diameters so as to change the speed of rotation of the output shaft 31 of said speed changing device. The output or drive shaft 31 of the device 28 may be connected by means of belt 32 to a horizontally disposed screw 33 mounted between rails 26 and extending the entire length of said rails.

It is to be understood, of course, that the motivating means instead of taking the form of an electric motor may comprise any desirable prime mover, and also that any conventional speed reducing device may be substituted in place of the one shown, or if it is found desirable, the mover may be directly connected to the screw 33.

A carriage 35 comprising inverted U-shaped members 36 and 37 connected by bars 38 and provided with wheels 39 may be mounted upon the upper portion of the machine, said wheels being adapted to roll upon tracks 26. The frame of the carriage 35 may be maintained rigid by the provision of reinforcing elements 40 and 41, respectively, mounted upon opposite sides of said carriage frame. 7

The depending extremities of the U-shaped members 36 and 37 may terminate in bearings 42 and 43, which may in turn be adapted to support shafts 44 and 45, respectively. Levers 46 having bearings 47 may be rotatably mounted upon shaft 44, said levers being interconnected by means of spacing bar 48. The opposite ends of each of said levers 46 may be provided with bearings 49, which may support rotatable shaft 50. Rigidly mounted upon shaft 50 is a grinding wheel 51 which in the preferred embodiment of my invention may be provided with a plurality of annular grooves 52, the number of said grooves and the width and depth thereof being dependent upon the number of glass plates to be ground and the thickness of said plates, respectively.

A plurality of levers 53 may be journalled by means of bearings 54 upon shaft 45, the mounting thereof being similar to that of the bearings 47 upon shaft 44. The opposite end of levers 53 may be provided with bearings 55, similar in construction to bearings 49, said bearings being adapted to support shaft 56 upon which wheel 57 may be mounted, said wheel being substantially similar in construction to wheel 51. a

An electric motor 58 may be mounted upon the upper portion of carriage 35 and may be operatively connected by means of belt 59 to shaft 45, said shaft in turn being operatively connected to shaft 44 by a sprocket chain 60. By this arrangement both of said shafts 44 and 45 may be rotated synchronously, or, if desired, the sprocket wheelsmounted on each of said shafts may be of different diameters, in which case shafts 44 and 45 may be rotated at different speeds.

Shaft 44 may be operatively connected to shaft 50 by sprocket chain 61, and likewise shaft 45 may be connected to shaft 56 by a similar sprocket chain 62. By this arrangement rotation may be simultaneously imparted to both of the grinding wheels 51 and 57 and, if desired, said wheels may be rotated at the same speed, or the angularvelocities of the wheels may be different.

A track 63 may be mounted at each end upon frames 1 and may be adapted to support wheels 64 and 65. Wheel 64 may be mounted upon shaft 66, which in turn may be rigidly connected to block 67, said block being slidable within guides 68. The guides 68 may be mounted upon one of the levers 46. By this arrangement the entire swingable assembly, including levers 46 and grinding wheel 51, maybe supported upon wheel 64, which in turn is dependent for its support upon track 63.

To adjust the elevation or depression of grinding wheel 51 relative to its supporting wheel 64,

block 67 may be moved vertically between guides 68 by means of screw 69 threaded into said block. Said adjustment may be readily made by turning hand wheel '70 shown in Fig. 1, which in turn rotates shaft 71, bevel gears 72 and 73, which latter gear may be mounted upon screw 69. In this manner the relative elevation or depression of grinding wheel 51 may be readily changed with respect to wheel 64, and hence with respect to track 63.

Wheel 65 may be loosely mounted upon shaft 56 and is not adapted to turn with said shaft. It can readily be seen by this construction that the swingable assembly comprising levers 53 and grinding wheel 57 is supported by wheel 65, which in turn depends for its support on track 63.

Taking the, entire carriage construction into consideration, including the swingable assembly comprising levers 46 and grinding wheel 51 and levers 53'and grinding wheel 57, it can be seen that the speeds of rotation of said grinding wheels may be maintained the same, or said speeds may be changed relative to each other and the relative depression or elevation of the grinding wheel 51 with respect to 57 may be maintained the same,

.or the axis of wheel 51 may be raised above or lowered below the axis of wheel 51. By providing this flexibility of adjustment of the two grinding wheels, if the surface of one wheel wears faster than the grinding surface of the other and it is desired to maintain both wheels at an equal elevation or depression, the same may be accomplished by adjusting the elevation or depression of the adjustable wheel 51.

A block 74 may be longitudinally disposed upon the upper portion of the platform 8 and may extend substantially the entire length of said platform, said block being provided with a plurality of parallel slots 75. Glass plates 76 may be disposed upon block 74, the lower edges of said plates being adapted for insertion in slots 75. The base 77 of each of the slots may be provided with a resilient material such as sponge rubber or the like to permit limited independent downard movement of the individual glass plates. The arrangement is such that when grinding wheels 51 or 5'7 bear upon the upper edges of the plates by the provision of the resilient supports '77 said upper edges may be maintained in the same plane regardless of slight differences in the width of the glass plates. In this manner substantially the same stock will be ground from the edges of each of the plates.

It is to be understood, of course, that the blockv '74 may be provided with any number of slots 75, corresponding to the number of grooves in the wheels 51 and 57; and also. the width of each of the slots may conform to the thickness of the glass to be ground, as also will the width of the grooves in the wheels 51 and 57.

A plurality of I-sectioned irons '78 may be spacedly mounted upon each of the frames 1, said irons extending substantially the entire length of the machine. Each of said I beams '78 may have associated therewith a spacing bar 79 which may be of a-length equal to the length of the I beams '78. A plurality of guides 80 may be disposed adjacent said bars '79 and may be positioned vertically with respect to said bars. Guides 80 may be provided with a longitudinally extending central slot 81 and may also be provided with clamps 82 disposed along the length of said guides and spaced from each other a distance equal to the spacing of the bars 79. Clamps 82 may be rigidly mounted upon guides'80 and may be provided with a locking screw 83 which may be adapted to make contact with the rear portion of the bars 79. In this manner guides 80 may be maintained rigidly with respect to the bar 79, and as can readily be seen said guides may be optionally spaced along the lengthof said bars '79, and as will be hereinafter more fully described the spacing of adjacent guides 80 with respect to each other will depend upon the length of the glass plates 76 which are to be ground.

The ends of the glass plates 76'may be spaced relative to each other and may be maintained in a fixed spaced relationship by means of end supports 84 which may be L-shaped, one leg 85 of which is provided with a plurality of slots 86, whereas the other leg 87 may be adapted to be adjustably mounted upon the guide rod 80. The slots 86 provided in the leg 85 may be interspersed by projections 87 which may terminate in points of reduced section so as to permit the ready insertion and removal of the glass plates '76 into said slots. The leg 87 may have mounted thereon a projection 88 which may be of a thickness equal to the width of the slot 81, said projection being adapted to be inserted in said slot. The bolt 89 may be positioned through leg 87 and block 88 and may be adapted to maintain the member 84 in rigid relationship with the guide rod 80. Said bolt may be tightened by means of a wing nut 90.

It can readily be seen that any number of end supporting members 84 may be utilized in conjunction with the machine, depending upon the length and the number of glass plates to be cut, that is, the number of plates placed end to end upon the platform 8. As shown best in Fig. l, a member 84 will be interposed between each series of vertically positioned plates.

In operation guide rods 80 may be so spaced from each other as to conform with the length of the glass to be ground. Platform 8 may be so adjusted in an upwardly or downwardly direction to conform with the width of the plates to be ground. The plates may be inserted in the grooves 75 of the block '74 and the ends of said plates may be maintained in spaced relationship with respect to each other by means of an appropriate number of end supporting members 84 mounted upon guide rods 80.

The relative elevation or depression of the platform may be accurately determined by means of pointer 91 mounted upon platform 8, which pointer is adapted to ride adjacent a vertically positioned gauge 92.;

When the plates '76 have been suitably mounted upon the platform 8 the carriage 35 may be brought to its extreme position upon the right end of the rails 26. The motor 27 may be set in operation and screw 33 may be revolved at a desired speed-by suitably adjusting the speed control mechanism 28. Motor 58 -mo unte d upon carriage 35 may be set into operation, thereby rotating grinding wheels-51 and 57. Carriage 35 may then be set in motion by operatively connecting the same to the rotating screw 33, said connection comprising a suitable clutch 93 which may be engaged or disengaged by means of operating rod 94. Upon engagement of the clutch 93 with the screw 33 carriage 35 will movetoward the left and by suitable adjustment of the elevation or depression of the platform 8, and also by manipulation of the hand wheel 70 wheels 51 and 57 may be so adjusted as to grind a desirable portion of the edges of the glass plates.

As has been hereinbefore described the grinding surface of wheel 51 may be lowered below the grinding surface of wheel 57, or it may be raised above the grinding surface of wheel 57 by manipulating hand wheel 70, or if desired the grinding surfaces of said wheels may be maintained in the same horizontal plane. By manipulating the relative elevation or depression of the grinding surfaces of the wheels each wheel may be so adjusted with respect to the upper edges of the plates as to grind a different amount of stock therefrom, or as has been here'inbefore mentioned differences in diameter of the wheels 51 and 57, for instance, due to. abnormal wear of one of said wheels, may be compensated for by said adjustment. Hence, the possibility suggests itself of utilizing grinding wheels of different diameters and yet maintaining their grinding surfaces in any desired plane.

After this adjustment has been made the same will be maintained constant inasmuch as the elevation or depression of the grinding wheels is thereafter dependent upon the passage of the wheels 64 and 65 over the track 63. It can be seen by this that the grinding wheels 51 and 57 may be automatically adjusted for grinding the edges of the glass plates along a straight line or along any desired curved line merely by changing the surface of the track 63 over which wheels 64 and 65 ride. For instance, in the grinding of the edges of Windshields it may be desirable to produce an edgeupon the lower side of the windshield which is a concave to conform to the cowl of the automobile. To accomplish this, track 63 instead of presenting a truly horizontal surface may be constructed in removable sections, which may be replaced by corresponding sections having curvilinear upper surfaces.

Referring particularly to Fig. 15 a section of this type is shown at 95, said section being provided with a concave upper edge 96. Said section may be mounted upon the machine in any sud h ve

desirable manner, for instance, by means of studs 97 which. may be inserted in suitable apertures provided in a supporting bar (not shown) adjacent the passage of the wheels 64 and 65. The sections 95 may be spaced end to end and said spacing may be so arranged as to bring the concave portion 96 at a point adjacent the longitudinal center of the glass plates'f'76. this manner, as the carriage passes-from right to left wheels 64 and as they ride along the curved sections will permit the grinding wheels 51 and 57 to be depressed, and hence concave upper surfaces will be ground upon the upper edges of the plates 76.

A bar 98 may be mounted upon the side of one of the rails 26 and may extend substantially to the end of said rail, said bar being adapted to receive a lug 99 which may be operatively disposed at any desired position along the length of the bar. The clutch operating handle 94 may be provided with a downwardly extending portion 100 which, when the carriage travels from one end of the machine to the other, passes along the upper surface of the bar 98. It can readily be seen that when said downward extension passes into contact with lug 99 clutch 93 will be disengaged from screw 33 and hence the motion of the carriage 35 will be stopped. The opposite end of handle 94 may be provided with an outwardly extending portion 101 by which means clutch 93 may be manually operated to engage or disengage the screw 33.

Disposed at points along the track '63 and to the right of lug 99 is a shoe 102 which may be fastened to rail 63 by means of screw 103, the

upper surface of said shoe being raised approxi have one of its ends beveled, as shown best at 104 I in Fig. '7, so as to permit wheel 65 travelling along rail 63 to pass upwardly over said beveled surface to the uppermost part of shoe 102. Simultaneously with the contacting of wheel 65 with shoe 102 flange 105 forming a portion of wheel 64 may contact the beveled portion 106 of shoe 107 spaced upon rail 63 a distance equal to the spacing in a horizontal direction of the shafts 56 and 66.

It can readily be seen that when wheel 65 and flange 105 contact, respectively, shoe 102 and shoe 107 the levers 53 and 46 will be simultaneously rocked in an upwardly direction thereby raising grinding wheels 57 and 51 from the upper edges of the glass plates '76. When the wheels 65 and 64 occupy the positions shown in dotted lines in Fig. '7 extension 100 of the clutch control handle 94 contacts lug 99 and hence the motion of carriage 35 is stopped while thegrinding wheels are maintained in upraised position.

Member 108 may be mounted at one end upon lever 446 in any desired manner, and the arrangement is such that said member and said lever may move upwardly or downwardly simultaneously. The outer end of member 108 may be provided with lug 109 which when grinding wheel 51 is raised, that is, when wheel 64gis in the position shown in dotted lines in Fig. '7, travels upwardly above shoulder 110 provided upon lever 111 pivotally mounted upon the framework of the carriage 35, as shown best at 112 in Fig. 2. When the swingable assembly comprising levers 46, grinding wheel 51 and member 108 raises, lever 111 may be rotated in a counter-clockwise direction, and when lug 109 passes the uppermost portion of shoulder 110 lever 111 will swing in a clockwise direction by gravity or by the impelling force of a spring (not shown), and will tend to maintain member 108 in its upraised position, that is, grinding wheel 51 will be maintained in a position approximately one-quarter of an inch above the upper edges of the glass plates 76. A second lever 112 may be pivotally mounted at 1-13 upon the frame of carriage 35 and may be provided with an outwardly extending shoulder 114. An extension 115 may be carried by one of the levers 53 which when said lever is raised by the contact of wheel 65 with the shoe 102 is raised above the upper surface of shoulder 114, thereby swinging lever 112 in a counter-clockwise direction which subsequently returns in a clockwise direction and holds levers 53, and hence grinding wheel 57, in an upraised position.

At this point forward motion of the carriage 35 being stopped, and grinding wheels 51 and 57 being raised above the upper edges of the plates 76, the carriage may be returned to the right end of the machine by means of hand wheel 34. Hand wheel 34 may be operatively connected to a sprocket wheel (not shown) over which sprocket chain 34' may pass. Both ends of saidsprocket chain may be suitably attached to the frame of carriage 35 and may pass over a second sprocket wheel (not shown) disposed at the opposite end of the machine. Consequently, by rotating hand wheel 34 said sprocket chain will be moved in an obvious manner and carriage 35 may be returned manually to its starting position. A new series of glass plates may then be mounted upon platform 8 in a manner which has been hereinbefore described. In addition, grinding wheels 51 and 57 may again be lowered to the upper surfaces of the glass plates '76 in a manner to be hereinafter more fully described.

A shoe 116 mounted by means of screw 117 upon the lower portion of rail 63 may carry a trip lug 118 which may be disposed outwardly from said shoe a relatively short distance. Spaced from shoe 116 is another shoe 109 mounted in a similar manner upon the lower portion of rail 63, said latter shoe carrying trip lug 120 which may extend outwardly from rail 63 a relatively greater distance than the outward extension of trip lug 118. The spacing of shoes 116 and 119, or more strictly speaking the spacing of lugs 118 and 120 is equal to the distance between levers 111 and 112, and the arrangement is such that the lower end of lever 112 contacts trip 118 simultaneously with the contacting of the lower end of lever 111 with trip 120. Both shoes 116 and 119 may be mounted upon rail 63 at the opposite end thereof from shoes 102 and 107. Consequently, when carriage 35 has been moved to its extreme position toward the right as-viewed in Fig. 1 said trips contact the raised levers hereinbefore mentioned and permit grinding wheels 51 and 57 to descend to the upper edges of the glass plates '76. Clutch control bar 94 may then be actuated to engage clutch 93 with screw 33, thereby again moving carriage 35 with grinding wheels 51 and 57 in operative contact with the upper edges of the glass plates and wheels 64 and 65 in operative relationship with the upper edge of rail'63.

When reference is made to rail 63 a rail with a horizontal upper surface is contemplated, or a rail comprising a plurality of sections such as that shown at 95 in Fig. 15 may be contemplated, or in general a rail having any desirable contour dependent upon the. particular configuration or curvature desired to be imparted to the upper surfaces of the glass plates upon platform 8. It

is to be understood, of course, that our invention is not intended to be limited to the grinding of glass plates inasmuch as other materials, such as marble slabs, steel sheets and the like may be ground in a similar manner.

If desired, instead of raising both guide wheels 64 and 65 simultaneously above the surface of the rail 63 the same may be raised in series by the provision of an upraised portion of rail 63 (not shown) that is, one end of the rail 63 comprising a section of a minimum length equal to the distance between shafts 66 and 56 may be upraised, for example, approximately one-quarter of an inch above the remaining portion of said rail. This construction is not shown in the drawings, but will be obvious to anyone skilled in the art.

The same principle may be applied to the lowering of the grinding wheels to the work at the opposite end of travel of the carriage, that is, at its starting position, in which case one trip corresponding to either trip 118 or trip 120 may be provided in conjunction with an upraised section of rail 63. In this manner grinding wheels 51 and 57 instead of being lowered simultaneously will be lowered in series. This construction is also not shown in the drawings, but in view of its simple character will be obvious to those skilled in the art.

To cool the grinding wheels 51 and 5'7 and the the plates 76 a liquid such as water may be passed through flexible hose 121, pipe 122 and pipe 123 from whence it may be passed through branch pipes 124 and 125 disposed adjacent wheels 51 and 57 and discharged through jets 126 upon .the surfaces of said wheels. Of course, any other desired cooling arrangement may be utilized inasmuch as the cooling means forms no part of my invention.

By the use of the term plates as used in the specification and claims is meant glass plates, marble plates, or the like, or in general any type plate which may be abraded by a suitable grinding wheel.

We claim as our invention:

1. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinally movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, and a track longitudinally disposed upon said frame upon which said guide wheel is supported.

2. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinally movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, an adjustment for moving the guide wheel relative to said swingable mounting for the grinding wheel, and a removable track longitudinally disposed upon said frame upon which said guide wheel is supported.

3. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinally movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, and a track longitudinally disposed upon said frame upon which said guide wheel is supported comprising a shoe adjustably positioned upon said track upon which said guide wheel rides when the carriage reaches the end of its travel.

4. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinally movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, a track longitudinally disposed upon said frame upon whichsaid guide wheel is supported, means for raising said grinding wheel from the edges of said plates at the end of travel of said carriage upon said frame, and means for maintaining said wheel in upraised position while said carriage travels to its initial starting position upon said frame.

5. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinal- 1y movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, a track longitudinally disposed upon said frame upon which said guide wheel is supported, means for raising said grinding wheel from the edges of said plates at the end of travel of said carriage upon said frame, means for maintaining said wheel in upraised position while said carriage travels to its initial starting position upon said frame, comprising a lever pivotally mounted upon said carriage, an offset shoulder upon said lever, and a lug upon said swingable mounting for engaging said offset shoulder when said grinding wheel is raised above a predetermined position.

6. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinally movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, a track longitudinally disposed upon said frame upon which said guixzle wheel is supported, means for raising said grinding wheel from the edges of said plates at the end of travel of said carriage upon said frame,

means for maintaining said wheel in upraised position while said carriage travels to its initial starting position upon said frame, and means for lowering said wheel into contact with the edges of said plates when said carriage progresses forwardly from its initial position.

7. In combination, a frame, a platform mounted upon said frame for supporting a plurality of plates in a vertical plane, a carriage longitudinally movable upon said frame, a grinding wheel swingably mounted upon said carriage, means for rotating said grinding wheel in operative contact with the edges of said plates, means for controlling the elevation or depression of said grinding wheel relative to the longitudinal axis of said plates during its passage over said plates, comprising a guide wheel mounted upon the grinding wheel swingable mounting, a track Iongitudinally disposed upon said frame upon which said guide wheel is supported, means for raising said. grinding wheel from the edges of said plates at the end of travel of said carriage upon said frame, means for maintaining said wheel in upraised position while said carriage travels to its initial starting position upon said frame, and means for lowering said wheel into contact with the edges of said plates when said carriage progresses forwardly from its initial position, comprising a trip lug mounted upon said track for contacting said lever and releasing the swingable mounting lug from the shoulder upon the lever.

EDWARD EDWARDS.

KURT W. SOMMER.

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