US2473670A - Grinding machine - Google Patents

Description

June 21, 1949. ,,w" s N 2,473,670

1 GRINDING MACHiNE Filed June 7, 1945 e Sheets-Sheet 1 I no 130 105 a N j. q-

C0 N 5 H a I ll g IH m INVENTOR JOHN C. WXLEON.

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ATTORNEYS June 21, 1949.

J. 0. ILSON GRINDING MACHINE 6 Sheets-Sheet 5 Filed June 7, 1945 I =IIII=I \\\\\\\\\\\\\\.IIII.

INVENTOR JOHN CJAJILEDN W & ATTORNEYS June 21, 1949. Y J; C(WILSON 2,473,670

' GRINDING MACHINE Filed June 7, 1945 I e Sheets-Sheet 4 5&5 T

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mu I 102. v 112 4 INVENTOR. i 5 JOHN awzascw 5 TTURNEVS June 21, 1949. J.IC. WILSON 2,473,670

GRINDING MACHINE v Filed June 7, 1945 6 Sheets-Sheet 5 iii 2115 EDE E El] SE 82 /H L l l .vxssszn MOTOR X) a l 2 17/ I69 3 EEIE IN VEN TOR. JOHN C. WILSON FJTTURNEEJ'S June 21, 1949. J, c, w soN 2,473,670

GRINDING MACHINE Filed June 7, 1945 6 Sheets-Sheet 6 INVENTOR. JUHN c. wrzsozw HTTURNEP'S i; 14 BY Patented June 21, 1949 UNITED STATES PATENT OFFICE GRINDING MACHINE Application June 7, 1945, Serial No. 598,031

20 Claims. 1

Thi invention relates to grinding machines and, particularly, to grindingmachines having Wheel dressers associated therewith. More parexact contour by bringing the wheel and the roll together while not rotating, and under a predetermined pressure thereafter driving the roll and wheel at the same peripheral speed and'forcing the two together. The thrust of the roll on the Wheel is radial and the resulting pressure breaks the bonding material of the wheel which maintains the abrasive particles thereof in position. It has been found that complex and highly accurate contours may be transferred to a grinding wheel in this manner so that the resulting work- 7 pieces are satisfactorily accurate.

While it is to be preferred that the crushing roll be of hardened steel, it has been found that the use of a soft steel is satisfactory where the tolerances are not too close and it is not required to use the dresser over a long period of time.

Rolls of long life and excellent performance have been formed of a high speed steel having an anal: ysis of 18% tungsten, 4% chromium and 1% vanadium, the rolls having been hardened to a Rockwell of 65 to 67 C scale.

A preferred method of grinding when the wheel has been crush dressed is known as plunge grinding; which consists of a single pass across the workpiece, removing as much as 0.080 inch of material, and producing a finished unit. How' ever, the work may be operated by taking several passes across it with a wheel and equally good results will obtain.

In the dressing of the wheel, it is important I that there be a minimum of relative movement between the engaged surfaces of the wheel and roll to prevent the lapping out of the roll by the wheel.

Accordingly, it is a primary object of the present invention to provide in combination with a grinding wheel, a crushing roll for dressing the Wheel to a predetermined contour.

It is still another object to provide an automatic control means for controlling the dressing of a grinding wheel by a crushin roll which prevents lapping out of the roll.

It is still another object to provide a control means in connection with a crushing roll for exactly determining the amount of material removed from the grinding wheel by the crushin roll during dressing.

It is still another object to provide automatic means for dressing a grinding wheel by a crushing rol l These and other objects and advantages will become more apparent upon reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a grinding machine equipped with a crushing type dresser;

Figure 2 is a section through a portion of the elevating mechanism for the grinding wheel and is taken approximately on the line 2-2 of Figure 1;

Figure 3 is a section taken on the line 3-3 of Figure 2 also illustrating a portion of the elevating mechanism for the wheel;

Figure 4 is a plan View, partly in section, of the dressing attachment mounted at the right end of the grinding machine table in Figure 1;

Figure 5 is a section taken substantially on the line 55 of Figure 4;

Figure 6 is a longitudinal section taken on the line 6-6 of Figure 5;

Figure '7 is a view of a modified structure for automatically elevating the crushing roll toward the wheel;

Figure 7a is a view showing the solenoid actuator for the mechanism of Figure 7;

Figure 8 is a fragmentary view taken substantially on the line 8-8 of Figure 1 showing one form of mechanism for limiting the down feed of the wheel;

Figure 9 is a diagrammatic view of an electrical circuit for controlling the actuation of a grinding machine and dresser;

Figure 10 is a perspective view of a modified arrangement wherein the wheel is driven against the dressing roll; and

Figures 11 to 17, inclusive, are diagrammatic views illustrating a typical grinding and dressing 037018.

General arrangement Referring to the drawings, there is illustrated in Figure 1 a grinder having a bed l0 upon which is reciprocably mounted the Work-piece supporting table 12. A column l4 attached to the bed I0 or otherwise suitably fixedly mounted adjacent thereto reciprocably carries a saddle I6 which supports a wheel head structure generally indicated at I8. The saddle I6 is vertically reciprocable on suitable ways integral with the column by a mechanism which is not shown but which may comprise a nut and lead screw arrangement of any well known and suitable type.

The wheel head structure at I8 is horizontally reciprocable in the saddle I6 in the V-ways 20. preferably by fluid operable means mounted in the saddle.

The table I2 mounts at one end thereof a dressing attachment generally indicated at 22 which comprises a shaped roll 24 adapted for crushing the grinding wheel 26 to any predetermined contour.

The table I2 is adapted for reciprocation by a motor means, preferably fluid operable, which is mounted in the bed I and controlled as to speed and direction of movement b any Well known control arrangement.

The means for lowering and elevating the saddle I by manual means consists of the hand wheel 28 which is connected through suitable shafting with the vertical screw which drives a nut carried by the said saddle. The construction of the elevating means is more particularly shown in Figures 2 and 3.

Elevating mechanism The hand wheel 28 is keyed by a key 30 with a sleeve 32 rotatably journalled on the shaft 34. The shaft 34 has keyed to the right end thereof a clutch member 35 adapted for reciprocation by an arm 38 into and out of engagement with the toothed end 40 of the sleeve 32. The arm 38 is connected to be activated by the hand lever 39 so that the sleeve 32 may thus be selectively connected or disconnected to the shaft 34, the shaft 34 being drivingly engaged with the saddle elevating screw.

The elevating mechanism also comprises a pair of plungers 42 and 44 which comprise opposed working areas and a central rack portion, the latter being adapted for engagements with the toothed sector 46 and the gear 48, respectively. The toothed sector 46 carries the pawls 50 which engage the teeth around the periphery of a ratchet wheel 52 which is keyed to the sleeve 32. Reciprocation of the plunger 42 is adapted for counter-clockwise rotation of the ratchet 52 which brings about the down feed of the saddle I3. In order to regulate the particular amount of downfeed for each reciprocation of the plunger 42, there may be provided the adjustable screw 54 which may be set to abut the toothed sector 46 at any predetermined point of its travel. Fluid is conducted to opposite ends of the plunger 42 through the passages 56 and 58 from a fluid source and valve arrangement, not shown. As will be explained hereinafter, the valve is preferably solenoid operated for bringing about the reciprocation of the plunger 42.

The plunger 44 is similarly reciprocated by means of fluid conducted thereto from a solenoid operated distributing valve and is adapted, through the gear 48 and the gear 60 to actuate a gear 62 carried by the member 64 which carries the pawls 66. The pawls 63 are disposed oppositely to the pawls 50 and are adapted for engagement with the toothed periphery of a ratchet wheel 68 keyed to the sleeve 32. Reciprocation of the plunger 44 is operable to bring about the retracting movement or upfeed of the saddle IS.

The hand wheel 28 may be actuated by the handle 68 thereon or a Vernier setting of the same may be had by means of the knob I0 which drives through a pinion I2 into a rack I4. The periphery of the hand wheel 28 is preferably graduated in any convenient manner and indicates against a fixed index mark so that the exact amount of up and down feed of the saddle I3 may be noted and the exact position of the wheel relative to the workpiece noted. These divisions are usually graduated to .0005 inch of movement of the saddle IS.

The hand wheel 28 also mounts an adjustable stop or cam member I6 which is adapted for contacting a plunger "I3 carried on a bracket as the wheel 28 moves in the downfeed direction. The bracket 80 is pivoted on a bolt 8! and when the cam surface 11 of the member I6 engages the plunger '38 the bracket is tilted. The tilting of the bracket actuates a limit switch LSI by the plunger 83 of the switch and the plunger 85 of the bracket. The cam I6 is adapted for being partially adjusted around the periphery of the hand Wheel 28 by a toothed shoe 82 which mounts the said cam and is engaged by a pinion 84 which is rotated by the lever 86, the latter being stopped in various positions of adjustment by the plunger 88.

Dressing attachment The dresser 22 is illustrated in Figures 4, 5 and 6 wherein it will be seen to comprise a bed memoer 500 which is mounted on the machine bed I2 and aligned therewith by a plurality of keys I02. The bed I00 comprises the upstanding side portions IS4 which rotatably receive, at the trunnions I05, one end of an auxiliary bed I08. The bed I83 supports at one end thereof the motor I I0 which drives through the V pulley II2 and V belt II 4 and V pulley H6 connected with the shaft IIB mounting the crushing roll 24.

The shaft H8 is journalled in precision anti- 1 friction bearings as at I22 thereby accurately to support the crushing roll as it is driven in rotation.

The bed I08 carries a pair of wear pads I24 at the endopposite the trunnions I06 which are engaged by the eccentric shaft I26. The shaft I26 extends laterally through the walls I04 of the bed I 00 and has connected to one end thereof a worm and wheel arrangement at I28 which is adjusted and locked into position by means of the knurled hand wheels at I30 and I3I, the latter locking the worm in any position of adjustment and the former being operable to adjust the worm when the locking wheel is loosened.

A cross bolt at I32 passes through slots I34 in the walls I04 and is locked into position by a nut I86 so that the bed I08 may be tilted relative to the bed I00 and clamped into position.

The roll at 24 is preferably of hardened steel and has any desirable contour preformed thereon. As mentioned before, the roll 24 may, in certain instances where the tolerances and number of workpieces to be operated will permit, be

formed of a soft steel.

Electrical circuit of Figure 9 the normally open start button I50 and the normally closed stop button I52. Th switch I50 is bypassed by the normally open blades AI so that depressing of the switch I50 brings about the energization of the coil A and the holding thereof through the blades AI.

A second pair of blades A2 of the contactor A are serially connected with the wheel head motor I54 which drives. the wheel 26. The motor I54 is bypassed by the normally closed blades A3 and the adjustable resistor I56.

Also connected between the power lines LI and L2 is a contactor B in series with the normally closed limit switch LSI, the normally closed stop switch I58 and the normally open start switch I60. The switch I60 is bypassed by the blades BI so that depressing of the switch I60 energizes the coil B which is held by the blades BI until the switch I50 or the switch LSI is opened, the latter being the downfeed limit switch which is opened in response to the actuation of the plunger I8 by the cam I6.

A second pair of blades B2 of the contactor B are serially connected with a motor I62 which is adjustable in speed by means of a variable resistor I64. Other means of adjusting the speed of the motor will occur to those skilled in the art but, for the sake of simplicity, there has been shown the resistor I64. The motor I52 has fastened to the shaft thereof a cam I66 which is adapted for closing the switch S! which is serially arranged with the normally open contactor blades B3 and a solenoid I66. Rotation of the motor I 62 is adapted intermittently to close the switch SI thereby intermittently to energize the solenoid I68 which, in turn, is adapted for actuating the valve I6! which is connected to control the supply of pressure fluid to the plunger 42 for bringing about the downfeed of the wheel 26 and wheel head I8.

The contactor B also comprises the blades B4 which are connected in series with the motor I I that drives the crusher roll 24.

Operation of first embodiment In operation, a workpiece is mounted on the table I2, the wheel 26 having been previously dressed to the desired contour. The wheel is then adjusted to the proper height relative to the workpiece and the switch I 50 closed to bring about energization of the wheel driving motor I54. Thereafter, the table is moved to pass the workpiece beneath the wheel to perform the grinding operation. This plunge" cutting by a single pass of the work beneath the wheel produces a finished article but it will be understood that several passes could be taken with the wheel being intermittently fed downwardly to the desired depth.

After the work has been completed, the wheel is elevated as in Figure 12 and the switch I52 depressed to deenergize the contractor A and, thus, also, the wheel motor. When the contractor A is deenergized the blades A3 thereof close and complet a dynamic braking circuit through the resistor I56 and across the motor I54 in order rapidly to bring the wheel to a halt. As a precautionary measure the limit switch LS-2 may be provided in the circuit of the contactor A so that positioning-of the wheel over the crushing roll will automatically deenergize the wheel head motor. This may be accomplished by mounting the limit switch LS2 on the machine bed and providing a cam I53 on the table I2 in such a position that movement of the table to dressing position brings the cam against the switch. This positively prevents the engagement of the roll by the wheel while the latter is rotating.

The wheel and the roll are now brought together until they touch and a slight pressure is applied by rotating the downfeed wheel a predetermined amount. Then, the downfeed stop plunger and cam are adjusted to permit a predetermined feeding together of the said wheel and roll. This feeding together may comprise a very light dress if the wheel is frequently dressed or, a heavier dressing operation if the wheel is only intermittently dressed.

After the downfeed stop has been adjusted, the operator closes the switch I60 thereby energizing the contactor B and closing its associated blades, of which BI provides a holding circuit, B2 energizes the timer motor I62, B3 prepares the energizing circuit for solenoid I68, and B4 energizes the dresser motor H0.

The blades B2 energize the adjustable speed motor I62 which brings about, through the cam I66 and switch SI, an intermittent energizing of the downfeed solenoid I68. The exact amount and frequently of the downfeeding of the wheel will vary with the type of wheel and other conditions but normally a downfeed of about .0005" for every 1% revolutions of the wheel is satisfactory. This maintains the wheel and roll together under pressure and prevents any relative motion therebetween which could cause the roll to be cut by the wheel.

When the wheel head has been fed into the roll until the limit switch LSI is opened, the contactor B is deenergized and the motor I62 and motor IIO are deenergized. This condition is illustrated in Figure 16 wherein the wheel and roll are both halted but remain together under pressure. Thereafter, the wheel is retracted from the roll either manually by the handwheel 28 or by closing the switch S2 to energize the solenoid I69 of the valve III which, when thus actuated, directs pressure fluid to the left end of the plunger 44 as viewed in Figure 3. This moves the plunger rightwardly and, through the gears 48, 60 and 62 and the ratchet 68 and pawl 66, drives the sleeve 32 in wheel elevating direction. Thereafter, a new cycle of operations, beginning with a grinding operation, may be commenced.

By adjusting the roll to the precise height of the finished workpiece it is possible, at the end of the dressing operation, to move the wheel horizontally from the roll directly into working position without retracting it from the roll. In that case it is not necessary to elevate or to lower the head; the only vertical movement being the automatic downfeed thereof into the crushing roll.

While there is shown in the drawings a grinding machine having a stationary head and a reciprocable work support, it will be understood that a stationary work support and a reciprocable head is an alternate arrangement well known in the art which is equally well adapted for being equipped with the apparatus of this invention. In any case, the work and the wheel are first brought into working relation with a high relative surface speed and thereafter, to dress the wheel, the wheel and dressing roll are brought together under pressure, and are rotated together with substantially zero relative surface speeds while being automatically fed together.

Modification of Figure 7 In Figure '7 there is illustrated a modification wherein the crusher roll is fed into the Wheel rather than the Wheelinto the 'roQL In-Fi ure 7 the shaft of the worm of the worm and wheel arrangement for vertically adjusting the crusher r011 carries a worm wheel 200 which is engaged by a worm 202 whose shaft 203 carries a ratchet 204. A plunger and'pawl 206 is adapted for indexing the ratchet wheel 204- one notch each time the armature 208 is reciprocated. The limit switch LSI is carried on the upright I04 of the bed I and is adapted for being actuated by the plunger 2I0 carried by the auxiliary bed I08. The plunger 2I0 is vertically adjustable by a mechanism generally indicated at 2I2 which may comprise agraduated hand wheel and suitable gearing connected with the said plunger.

The electrical diagram of Figure 9 is equally well adapted for actuation of the feeding mechanism of Figure '7, merely requiring that the solenoid I68 be adapted for actuating the armature 208.

Operation of the embodiment of Figure 7 In the operation of the embodiment of Figure '7 after the grinding operation i completed, the wheel is fed up from the work and-is thereafter manually positioned over the crushing roll and thereagainst under pressure.

The operator then sets the plunger 210 downwardly the distance the wheel is to be dressed off. The start button I60 is then closed to energize the coil B to energize the dresser motor II 0 and the motor I62. Rotation of the motor I62 drives the cam I66 intermittently to energize the solenoid I68 to actuate the armature 208 and to drive through the ratchet 204, worm 202, and worm wheel 200, the eccentric shaft I26 thereby to elevate the crusher roll into the wheel. When the plunger I20 opens the limit switch LSI, coil B is deenergized thereby halting the dresser motor H0 and the motor I62.

As before, a new cycle of operation, commencing with a grinding step, may now be commenced.

Modification of Figure In Figure 10 there is illustrated a modified arrangement particularly adaptable to heavy wheels which would be apt to slip against the crushin roll and, therefore, to produce harmful wear.

In Figure 10 the wheel 300 is connected with the shaft of a motor 302 while a second motor 304 is provided which, through reduction gearing 305 and a clutch, such as the over-running clutch 301, is adapted for driving the shaft of the motor 302. The motor 302 drives the wheel at high speed independently of the motor 304 when a workpiece is being ground while the motor 304 drives the wheel at reduced speed when the motor 302 is deenergized in order to accomplish the dressing cycle.

There is mounted on the table 306 of the machine, a frame 308 which adjustably carries a bracket 3I0 in which is journalled a crushing roll 3I2. An eccentric shaft 3I4 is provided for vertically adjusting the roll 3I2, if desired. The roll 3! 2 is freely journalled on the bracket 3I0 and thus freely rotates when it is engaged by the wheel 300.

The electrical circuit of Figure 9 is adapted for actuating the modification illustrated in Figure 10 merely by connecting themotor 304 in the place of the motor I I0.

It will be evident that this invention provides means operable automatically to crush dress a grinding wheel so that the element of skill is largely eliminated from this critical operation. Improved life of the dressing roll and the grinding wheel and improved quality of the workpiece result.

It will be understood that I desire to comprehend within my invention such modification as may be considered to come within the scope of the claims.

I claim:

1. In a method of shaping a grinding wheel by a crushing roll; pressing the said wheel and said roll together; driving the said wheel and said roll at the same peripheral speedy and incrementally feeding the said wheel and roll towards each other durin continued rotation of said wheel and roll for a complete dressing cycle.

2. The method of shaping a wheel with a crushing roll which comprises, pressing the said wheel and roll together; driving the said wheel and roll at the same peripheral speed; and feeding one of the said wheel and roll toward the other in spaced increment during continued rotation of said wheel and roll for a complete dressing cycle.

3. The method of shaping a wheel with a crushing roll which comprises. pressing the said wheel and said roll together while stationary; driving the said wheel and roll in opposite directions and at the same peripheral speed; feeding the said wheel and roll together in increments during continued rotation thereof; and stopping the rotation of said wheel and. roll while the same are still pressed together.

4. The method of shaping a grinding wheel by a crushing roll which comprises; pressing the said wheel and roll together under pressure while stationary; driving said wheel and roll in opposite directions and at the same peripheral speed while maintaining said pressure; intermittently feeding said wheel and roll together by increments during continued rotation thereof; and stopping the rotation of said wheel and said roll while maintaining said pressure.

5. The method of shaping a grinding wheel with a crushing roll which comprises; pressing said wheel and said roll together under pressure while not rotating; rotating said wheel and said roll in opposite directions and at the same peripheral speed; intermittently feeding said wheel and said roll together at a rate such that there is not more than one increment of feed during one rotation of said wheel; and stopping said wheel and said roll while maintaining the same together under pressure.

6. The method of shaping a grinding wheel by a crushing roll which comprises; pressing the said roll and wheel together under pressure while the same are stationary; rotating the same at the same peripheral speed; intermittently feeding the said wheel and roll together during continued rotation thereof so that the wheel makes at least one complete rotation between increments of feed; andstopping said wheel and said roll while maintaining the same together under pressure.

7. In combination, in a grinding machine, a grindingwheel, a dressing roll, means for positioning said wheel against said roll under pressure, means for driving said wheel and said roll at the same peripheral speed, and means operable automatically during continued rotation of said wheel and roll to move said wheel and said roll toward each other in spaced increments of feed.

8. In combination, in a grinding machine, a grinding wheel, a dressing roll, means forpositioning said wheel against said roll under pressure while not rotating, means for driving said wheel and said roll in opposite directions and at the same peripheral speed, means operable automatically to feed said wheel and said roll toward each other in spaced increments of feed; and

means operable automatically to stop the rotation of said wheel and said roll while maintaining the same together under pressure.

9. In a grinding machine, a grinding wheel, a bed, said wheel and bed being relatively movable, a dressing roll mounted on said bed, means for relatively moving said wheel and bed to position said wheel against said roll under pressure, means selectively operable for driving said wheel and said roll at th same peripheral speed, and control means operable while said wheel and roll are so driven for feeding the same together in spaced increments of feed, said control means also being operable automatically to make said driving means ineffective thereby to stop said wheel and said roll after a predetermined total amount of feed while retaining said wheel and roll together under pressure.

10. The combination in a grinding machine of a grinding wheel, a table reciprocable relative to said wheel, a dressing roll, a frame supporting said roll carried by said table, manual means for positioning said wheel against said roll under pressure, driving means energizable to drive one of said roll and wheel and therethrough the other thereof, and control means operable during the energization of said driving means to feed said wheel and roll together in predetermined chronologically spaced increments and also to deenergize said driving means to stop said wheel and said roll in response to a predetermined number of said increments.

11. In a grinding machine, a grinding wheel, a dressing roll, means supporting said dressing roll comprising a stationary bed and a sub-bed movable relative thereto cwhich mounts said roll, means for positioning said wheel against said roll under pressure, means for driving said wheel and said roll at the same peripheral speed, and control means operable automatically to feed said wheel toward said roll in increments which occur at a rate of not more than one for each revolution of said wheel, said control means also being operable automatically to halt said wheel and said roll after a predetermined number of said increments of feed while maintaining the same together under pressure.

12. In a grinding machine, a grinding wheel, a dressing roll operable to shape said wheel by pressure, a table reciprocable relative to said Wheel and supporting said roll, means for positioning said wheel against said roll under pressure, motor means for driving said roll and therethrough said wheel. switch means selectively operable to energize said motor means, and control means adapted to be eifective during the energization of said motor means and operable automatically to feed said wheel toward said roll, said feeding occurring in increments which are spaced at time intervals greater than that required for the said wheel to be driven through one complete rotation.

13. In a grinding machine, a grinding wheel, a dressing roll, a table mounting said dressing roll and also adapted for mounting a workpiece and reciprocable relative to said wheel, means for positioning said wheel against said roll, motor means for driving said roll and therethrough said wheel, switch means selectively operable for energizing said motor means, control means adapted for 10 being effective during the cnergization of said motor means for bringing about the feeding of said wheel into said roll in spaced increments, said control means including an adjustable timing means for bringing about said spaced increments of feed.

14. In a grinding machine, a grinding wheel, motor means operable to drive said wheel at grindingspeed for operating a workpiece, a table for supporting said workpiece reciprocable relative to said wheel, a dressing roll rotatably mounted on said table, motor means for driving said dressing roll at dressing speed, manual means for positioning said wheel over said roll, switch means operable to deenergize the motor means associated with said wheel when the latter is positioned over said roll, means for positioning said wheel against said roll under pressure, and control means operable automatically to accomplish the dressing of said wheel comprising a switch selectively operable to energize the motor associated with said roll, and a control circuit including a timing motor energized by the actuation of said last mentioned switch and operable to bring about the feeding of said wheel and roll together in increments which are spaced at time intervals greater than that required for the said wheel to turn through one complete revolution.

15. In a grinding machine, a grinding wheel, a first electric motor for driving said wheel at grinding speed for operating a workpiece, a normally open dynamic braking circuit connected to said first motor, a crushing roll for shaping said wheel, second electric motor for driving said crushing roll, manual means for positioning said wheel adjacent said roll preparatory to the crushing of the former by the latter, a limit switch adapted for being actuated by the wheel supporting structure when the latter is adjacent said roll for deenergizing said first motor and for completing said braking circuit for braking said motor and control means operable automatically during the energization of said second motor for feeding said wheel into said roll for accomplishing the dressing of the former by the latter.

16. In a grinding machine, a grinding wheel, a dressing roll, a bed supporting said roll and also supporting means for driving said roll in rotation, a sub-bed movably supporting said bed, means for positioning said wheel against said roll for the shaping of the former by the latter, and control means operable automatically for feeding said bed together with said roll toward said wheel during said shaping operation in spaced increments timed to occur at intervals at least as great as that required for the wheel to make one revolution.

17. In a grinding machine, a grinding wheel, a first motor for driving said wheel at grinding speed, a second motor for driving said wheel at dressing speed, a dressing roll for shaping said wheel, means rotatably supporting said roll, means for positioning said wheel against said roll under pressure while stationary, means for energizin said second motor, and control means energizable simultaneously with said second motor and operable automatically to feed said wheel and roll together in spaced increments thereby to bring about the shaping of said wheel by the removal therefrom of successive annular zones.

18. In combination in a grinding machine having a grinding wheel and a table reciprocable relative thereto, a dressing attachment comprising a dressing roll adapted for crush dressing said wheel, a bed supporting said roll, a sub-bed pivotaustere l 1 ally supporting saidbed and adapted for mount,- ing on. said table, motor means mounted on said bed for driving said roll, and means for adjust ing said beds relatively about their pivotal connection to any predetermined angularity for vertically positioning said roll.

19. In combination in a grinding machine having a grinding wheel and a table reciprocable relative thereto, a dressing attachment comprising a roll adapted for crush dressing said wheel, a bed on which said roll is rotatably supported and. on which is-also mounted a motor for driving said, roll in rotation, a sub-bed pivot-ally supporting. said bed; means including an eccentric shaft for? adjusting said bed about its pivotal connection with said sub-bed thereby to adjust the position of said roll, and means for positioning said eccentric shaft and locking the same.

20. In combination in a grinding machine havinga. grinding wheel and a table reciprocable relative thereto, a dressing attachment comprising a roll operable to crush dress said wheel, a bed. having means rotatably supporting said roll at one end thereof and a motor for driving. said 12 rolliat the, other end. thereof, a sub-bed, means pivotally-securing said bed to said sub-bed adjacentsaidmotor, an eccentric shaft positioned between saidbedsat the roll end thereof, and means for indexing said eccentric shaft in increments thereby-to rotate said bed about its pivot for adjusting the position of said roll.

JOHN C. WILSON.

REFERENCES CITED Theiollowing references are of record in the file of this patent:

"UNITED STATES PATENTS

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