US2792672A - Grinding machine and wheel dresser thereof - Google Patents

Description

May 21, 1957 o. CARLSEN ETAL 3 9 GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept- 7, 1954 ll Sheets-Sheet 1 -w 3| so 33 so P 4? FIG! R 00 w A 35 9 33 s4 I V l FIG. 2

INVENTORS LEONARD o. GARLSEN WILLIAM c. cmrcmsv B HARRY PEDERSEN ATTORNEY y 21,1957 L. o. CARLSEN ETAL 2,792,672

GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. 7, 1954 11 Sheets-Sheet 2 INVENTORS 3O LEONARD o. CARLSEN WILLIAM 0 CRITCHLEY BY HARRY PEDERS'EN ATTORNEY May 21, 1957 o. CARLSEN ET AL I 2,792,672

GRINDING MACHINE AND WHEEL DRESSER THEREOF 11 Sheets-Sheet 3 Filed Sept. 7, L954 INVENTORS LEONARD o. GARLSEN WILLIAM c. CRITCHLEY BY HARRY PEDERSEN QMJQM ATTORNEY V May 21, 1957 1.. o. CARLSEN ETAL GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. 7, 1954 11 Sheets-Sheet 4 FIG. l6-

INVENTORS LEONARD o. CARLSEN w AM o. c HLEY BY H Y- PEDER ATTORNEY FIG.

y 1, 1957 L. o. CARLSEN ETAL' 12,792,672

GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. '7, 1954 ll Sheets- -Sheet 5 INVENTORS LEONARD O. CARLSEM WILLIAM c. CRITCHLEY BY HARRY PEDERSEN film/.419

' ATTORNEY 1957 o. CARLSEN ET AL 2,792,672

GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. 7, 1954 1 11 Sheets-Sheet s I N 9 E g 9 I u. I'lll I II HI I il I 0 ll |i I O ID m I N 5| 1 1 I ||l|l|l|| I I g P l E I ID 9' v 2 INVENTORS LEONARD o. CARLSEN WILLIAM 0. CRITCHLEY BY HARRY PEDERSEN ATTORNEY May 21, 1957 L. o. CARLSEN ETAL 2,

GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. 7, 1954 ll Sheets-Sheet INVENTORS LEONARD o. GARLSEN WILLIAM c. CRITCHLEY BY HARRY PEDERSIEN awn/41m ATTORNEY May 21, 1957 o. CARLSEN ET AL GRINDING MACHINE AND WHEEL DRESSER THEREOF- Filed Sept. 7, 1954 ll Sheets-Sheet 8 INVENTORS LEONARD o. CARL WILLIAM 0. can BY HARRY PEDERSO ATTORNEY May 21, 1957 L. o. CARLSEN ET AL 2,792,672/

GRINDING MACHINE AND WHEEL DRESSER THEREOF I Filed Sept. 7, 1954 ll Sheets-Sheet 9 e9 68 I47 AIIEIIC E l7| I69\ I68 I56 /l45,|46 I58 I555 f FIG. I7 4 l57 I /\B l3,- 29

DRESS VWW las W T|59 I INVENTORS LEONARD o. GARLSEN WILLIAM c. CRITCHLEY BY HARRY PEDERSEN @Mum ' ATTORNEY May 21, 1957 L. o. CARLSEN 'ET AL GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. 7. 1954 11 Sheets-Sheet 10 FIG. l8

Y S 5 Y R L 05H 1 J m 4 MAmfl 0 0 9% D P am w M m m L OLR mwm Y B Q E F 5 6 W l W l ay 1957 r L. o. CARLSEN ETAL 2,792,672

GRINDING MACHINE AND WHEEL DRESSER THEREOF Filed Sept. 7, 1954 1 1 Sheets-Sheet 11 INVENTORS LEONARD o. CARLBEN WILLIAM C. CRITCHLEY BY HARRY PEDERSEN 41% AT TORNEY United States Patent i GRINDING MACHINE AND WHEEL DRESSER THEREOF Leonard 0. Carlsen, Rochester, William C. Critchley,

Brighton, and Harry Pedersen, Pentield, N. Y., assignors to The Gleason Works, Rochester, N. Y., a corporation of New York Application September 7, 1954, Serial No. 454,488 22 Claims. or. 51-33 The present invention relates to a grinding machine and a wheel dressing mechanism thereof. The invention is adapted especially but not exclusively to machines for grinding gears and other toothed par-ts.

According to the invention the teeth of a workpiece are ground with one or preferably a pair of conical abrasive wheels, the sides of the teeth being formed by plane or nearly plane surfaces of the wheels. The wheels are supported for feed motion to compensate for reduction in diameter due to Wear and dressing, such feed being in the direction of an element of the conical surface of each wheel. A separate dresser unit is provided for each wheel, and each unit is supported for feed motion relative to its wheel in at least approximately the direction of an element of the wheels conical surface that is perpendicular to the direction of wheel feed. The dresser feed is effected simultaneously with the wheel feed and is proportional thereto with the result that the position of the tooth forming surfaces of the wheels relative to the work is not changed as the result of the wheel dressing operation which succeeds each feed motion.

Each wheel dresser comprises a single dressing tool, preferably a diamond tipped tool, which dresses both the tip surface and the plane or nearly plane surface of the wheel and also the round at the juncture of these two surfaces. To enable this mode of operation the tool is carried by an arm which is rotatable on a bracket slidable in a dresser housing, and the housing in turn is mounted to pivot on its support. A single actuator, which preferably is in the form of a cylinder slidable relative to a piston secured within the housing, effects all of the dressing motions of the tool. During one part of its stroke the cylinder acts through a cam means to pivot the housing on its support to swing the tool across the tip of the wheel; during another part of its stroke it acts to rotate the arm on the bracket to move the tool over the round of the wheel; and during still another part of its stroke it acts to slide the bracket in the housing to move the tool across the plane or near plane surface of the Wheel.

The invention further provides a means for automatically maintaining the peripheral speed of the wheels substantially constant as their diameters are reduced by successive dressing operations. For this purpose a means is provided that is operated concomitantly with the aforementioned feed motions and that functions to increase the angular velocity of the wheel motors substantially in proportion to decrease of wheel diameter.

The foregoing and other objects and advantages of the invention will appear from the following description made with reference to the accompanying drawings, wherein:

Fig. 1 is a side elevation of the machine with the wheel dressers removed;

Fig. 2 is a plan view of the machine with the wheel supporting structure and the dressers removed; I

Fig. 3 is a vertical sectional view through the wheel supporting structure on the cradle of the machine;

2,792,672 Patented May 21, 1957 Fig. 4 is an elevational view looking toward the face of the cradle, showing the wheel supporting structure in a vertical plane perpendicular to Fig. 3;

Fig. 5 is a detail sectional view in planes perpendicular to Fig. 3, showing the wheel-advancing ratchet feed mechanism;

Fig. 6 is a sectional view in plane 6-6 of Fig. 5;

Fig. 7 is a detail view in a plane parallel the plane of Fig. 5 showing a brake for the ratchet feed mechamsm;

Figs. 8 and 9 are fragmentary elevational views of the lower one of the two dressers, as viewed respectively in the planes 8-8 and 9-9 of Fig. 3;

Fig. 10 is a detail sectional view in plane 10-10 of Fig. 9, parallel to the plane of Fig. 8.

Fig. 11 is a detail sectional view in planes indicated at 11-11 of Fig. 12, the major portion of the view being in the plane 11-11 of Fig. 9.

Fig. 12 is a fragmentary sectional view in planes 12-12 and 12A-12A of Figs. 8 and 11;;

Figs. 13 and 14 are detail sections respectively in planes 13-13 and 14-14 of Fig. 12;

Fig. 15 is a detail sectional view in plane 15-15 of Fig. 10;

Fig. 16 is a detail sectional view in plane 16-16 of Fig. 11;

Fig. 17 is a wiring and hydraulic diagram for the wheel feed and dresser mechanisms;

Fig. 18 is a sectional view of a Wheel-speed control device shown in Fig. 3;

Fig. 19 is a section in plane 19-19 of Fig. 18; and

Fig. 20 is an electrical diagram of the wheel speed control means.

Fig. 21 is a diagram in a plane through the axis of a work gear showing the effect which change of wheel diameter has on the height of arc of the root concavity of a work gear;

Fig. 22 is a diagram in a plane through the axis of the wheel, illustrating the effect of certain machine adjustments;

Fig. 23 is a diagrammatic view in plane 23-23 of Fig. 4;.and

Fig. 24 is a diagram similar to Fig. 22 and illustrating successive phases of the dressing operation.

As shown in Figs. 1 and 2 the machine has a frame 30 supporting a cradle 31 for to and fro rotation or oscillation about a horizontal axis 32. The cradle carries a pair of conical abrasive wheels W which rotate about axes 33 which are inclined to and offset from the cradle axis 32, the substantially plane faces 34 of the two Wheels representing tooth side surface of a generating gear whose axis is the cradle axis. The work gear G is-supported on a work spindle 35 journaled in work head 36 for rotation about horizontal axis 37. Usually the two wheels will be adjusted to operate in adjacent tooth spaces of the work gear. The work head is adjustable in the direction of axis 37 along ways 38 on a swinging base 39 which in turn is adjustable angularly, about a vertical axis, along arcuate Ways 41 on a sliding base 42. The latter is movable and slidable on rollers (not shown) along ways 43 on frame 30. By the several adjustments referred to the work gear G may be brought into the desired relation with the abrasive wheels W.

The machine contains a generating drive mechanism including motor 40 and overhead drive shaft 60 for rotating the work spindle 35 about axis 37 in time with rotation of the cradle about axis 32 whereby the surfaces 34 ofwheels W generate the tooth surfaces of the gear G. The machine includes an indexing mechanism which is operative during return rotations of the cradle and work spindle to advance the latter rotationally to thereby bring successive tooth surfaces of the Work into operative relation to the abrasive wheels. The machine also includes means for successively advancing or feeding the sliding base 42 along ways 43 to increase the depth of engagement of the abrasive wheels in the tooth spaces inventors, and Herman A. Male.

Referring to Figs. 3 and 4, each wheel W is secured to a spindle 44 that is journaled in "a wheel head 45 on anti-friction bearings 46. Mounted on each wheel head is a wheel drive motor 47 on whose armature shaft is a bevel pinion 43 meshing with a gear 49 on the spindle. Each wheel head has a cylindrical extension 51 supporting a sleeve which comprises the inner race of a linear ball bearing assembly 52, this assembly comprising a large number of balls spaced by a tubular cage and an outer tubular race that forms a part of a slide 53. The bearing assembly supports the wheel head for motion in the direction of cradle axis 32 to compensate for changes in diameter of the wheel. Such motion is effected by rotation of a screw 54 which is threaded to 'a nut 55 on the Wheel head, the screw being rotatable in an antifriction bearing 56 supported by slide 53. A bellows-like flexible seal 50 is extended between and connected to the head 45 and the slide 53 to protectithe surface of the bearing assembly 52.

Each of the two slides 53 is adjustable, vertically in Figs. 3 and 4, upon a separate cone distance adjusting plate 57, the latter in turn being adjustable, horizontally in Fig. 4, on a tooth angle adjusting plate 58 which is adjustable on the cradle 31 about axis 32. Upon first loosening clamp bolts 59 which secure each slide 53 to its plate 58, the slide may be adjusted vertically on the .plate by means of an adjusting screw 61. This adjustment enables the wheels to be adjusted toward or away from one another and also to be adjusted into either symmetrical relation to axis 32, for grinding straight bevel gears, or into asymmetrical relation, for grinding skew bevels. Adjustment of each cone distance 'plate57 may be effected by first loosening bolts 62 (and also one bolt 59) which :clamp plates 57 and 58 together, and then turning an adjusting screw 63, Fig. 3, to thereby move the wheel horizontally in Fig. 4- to thedesired position with respect to cradle axis .32.. The tooth angle adjusting plates 58 are moved about axis 32 relative to each other and to the cradle by means of a turnbuckle 64, after first loosening bolts 65 which clamp these plates to the cradle. As shown in Fig. v3 the cradle is rotatable about an axis 32 on roller bearings .66 on the cradle housing portion ofiframe 30.

The wheel feed mechanisms For advancing the wheels W to compensate for wheel wear, two feed mechanisms, one for each wheel are provided. Each such mechanism comprises aratchet wheel 67 afiixed to the feed screw 54 and operated by a piston and ratchet pawl device like that shown in Figs. 3 and 5. This includes a hydraulically actuated piston'68 slidable in a cylinder 69 which is a part of the slide 53, and a pawl 71 which is pivoted on a carrier 7-2 that is retatable relative to screw 54%. This piston is connected to the carrier by a pin-and-slot connection '73, and the pawl is urged toward the ratchet wheel 67 by a spring-backed plunger 74 on the carrier. As the piston is moved to .its limit position shown in Fig. 5, the pawl is moved out of engagement with the ratchet wheel by a pin 75, Fig. 6, Which is stationary with respect to parts 53 and .69 and which engages a tall 76 of the pawl. However on the together by springs.

operating stroke of the piston, as the member 72 is swung counterclockwise in Fig. 5, the tail 76 moves past the pin and the spring plunger 74 causes the pawl to engage :and advance the ratchet wheel. The stroke of the piston is limited by engagement of its shoulder 77 with a stop plate 78 which is supported rotatably by a shaft 79. This plate has six stop surfaces spaced at different radial distances from the axis of shaft 79, and by manual rotative adjustment of the plate any one of these surfaces may be brought into position for abutment by shoulder 77. By such adjustment the ratchet wheel may be caused to advance anywhere from one to six teeth for each operative stroke of piston 68. Each one-tooth advance of the ratchet wheel is effective through the screw and nut 54, 55, to advance the wheel head of the illustrated machine by one-thousandth of an inch. During its advance the Wheel head is held against angular movement about the axis of the sleeve bearing 52 by the engagement of guide rollers 81 with guide rails 32. The latter are stationary with respect to slide 53 and are parallel to axis 32. The rollers are carried by an arm 33 secured to part 51 of the wheel head.

For preventing unintentional rotation of the screw 54 a pair of brake shoes 84 and 85, Pig. 7, engage a brake drum 86 that is keyed to the screw, the shoes being urged The screw 56 may be manually rotated by means of a wrench, not shown, .applied to a socket '87 in the end of a tubular shaft 88. This shaft is rotatable in slide 53 and carries a gear 89 meshing with an idler gear 91 which is rotatable .on shaft 79, the idler in turn meshing with a gear 92 keyed to screw 54. The

stop plate 78 is adjusted by rotating a shaft 93 that is supported within tubular shaft 88 on two sets of needle bearings '94 separated by a spacer sleeve 94. Shaft 93 has :a wrench socket in its forward end that is accessible through socket 87. Keyed to the other end of shaft 93 is :a gear 95 meshing with a gear 96 that is keyed, together with plate 78, to shaft .79. Ball thrust bearings 97 separate gear 95 from tubular shaft 88, and gear 96 from .gear 91, so that the turning of shaft 83 will not cause shaft 93 to turn, and vice versa. A spring-backed plunger 98 retains gear 95 against its bearing 97. The gear 95 carries a stop pin 99 which extends into an arcuate slot in the housing around the gear, the pin abutting an end of :the slot when the .stop plate 78 is in either of its two :limit positions. A spring-backed ball 1G1 engages in one of six detents in the gear to hold die latter in any selected one .of the six positions thereof wherein it has a stop :surface positioned for abutment by shoulder 77 of the piston. To adjust the stop plate 78 to the desired one of these positions the shaft 93 is turned until pin 99 abuts one :end of its .=slot and the shaft is then turned back the desired amount which can be determined by counting the number of clicks of ball .101 into the detents in gear 95. Ittmay be noted that Fig. 5 shows the actual arrangement of theiscrew 54: and.shafts 79, 93 and 38, while Fig. 3 for clarity of illustration is distorted to show them as lyingin the same vertical plane.

The dresser mechanisms Aseparate dresser is also provided for each wheel W. the'two dressers being symmetrical to each other. Each dresser includes a diamond dressing tool D, Figs. 8 and 12, which is adapted to dress theplane face 34 and the tip surface 100 of the wheel, and also the small round or radius at the juncture of .these two surfaces. Each dresser mechanism is supported on a bracket 80, Figs. 2, 4, 8 and 9, which is secured rigidly to the related wheel head 45. Adjustable through a very small angle on an arcua'te way on the bracket, about an axis perpendicular tothe wheel axisand approximately tangent to the periphery of the wheel, is a dresser -sub-frame 132 supporting two rods, 103 and 194, which in the compositionv of the adjustment are parallel to an element w of;

the conical surface of the wheel 'W. The adjustment is greases effected by means of an adjusting worm 80" which is journaled in the bracket 80 and meshes with a worm wheel sector 102 on the sub-frame, the shaft of the worm having a calibratedknob 80a on its outer end. Rod 103 is secured to a dresser slide 105 and is supported on the sub-frame by means of linear ball bearings 106 while rod 104 is secured to the sub-frame and has fiat surfaces 107 engaged by rollers 108 carried by the slide, as shown in Figs. and 15. Each roller is supported on needle hearings on a pin which is secured to the slide 105. Also carried by the slide is a roller 109 engaging in a straight slot formed in a cam member 111, Figs. 4, 8, 9, 10 and 23, that is mounted on the vertical slide 53 which carries the wheel head on which the dresser is mounted.

The purpose of the earn 111 and roller 109 is to move the dresser carrying slide 105 inwardly along, or approximately along, element w of the wheel, i. e. inwardly along rod 104, concomitantly with and proportionately to the feed of the wheel head 45 by screw 54, the latter feed being in the direction of the cone element of wheel W that appears as a horizontal line in the vertical section, Fig. 3. As shown in the diagram Fig. 23, as the roller 109 is fed as a unit with the wheel head 45 in the direction of arrow 32', i. e. to the right in Fig. 3 in the direction of cradle axis 32, the action of cam 111 together with the guiding eifect of rod 104 is to cause the roller, and the dresser slide 105 which supports it, to move in direction 111'. That is, the roller and the dresser are given a motion relative to the wheel head 45 in the direction 104' of the axis of rod 104. As shown, greatly exaggerated, in Fig. 21 a gear G ground on the present machine has concave tooth bottoms, and the height of arc of the concavity increases with increase in face width of the gear and also with reduction in diameter of the wheel W. Thus as the radius of the wheel decreases from R to R the height of arc of the concavity for a given face width F is increased from H to (H +h).

Accordingly the dresser feed should be greater than the wheel feed by the distance h as the wheel radius is reduced from R to R. The ratio of dresser feed to wheel feed may be varied, to adapt the mechanism for gears of different face width F, by adjusting cam 111 on slide 53 about an axis which is coincident with the axis of roller 109 when the dresser carrying slide 105 is positioned for dressing a new wheel of regulation diameter. This axis is perpendicular to the cradle axis 32 and also to the axes of rods 103 and 104. The walls of the slot in the cam which engages the peripheral surface of the roller 109 are plane and of course parallel to the roller axis.

By reference to Figs. 21 and 22 it will be seen that with a regulation size wheel having radius R the point P of the gear will be produced by point p of the wheel surface 34, and that this point p is at distance H from tip surface 100 of the wheel. on the wheel which connects surfaces 34 and 100 is coincident with the adjustment axis 90 of sub-frame 102. When the wheel decreases to radius R so that surfaces 34 and 100 recede respectively to 34' and 100 the point P is ground by point p which is at the same distance from cradle axis 32 as is point 1. However the distance from p to surface 100 is greater by distance it than the distance H between point p and surface 100, with the result that the point C, the center of the round joining surfaces 34' and 100, is closer to cradle axis 32 and cone element w than is point C. This requires the dresser feed to be at the small angle A to the direction of cone element w. This angle may be varied, for gears of varying face width F, by adjusting the dresser sub-frame 102 on bracket 80 about axis 90. The angle A is greatly exaggerated in Fig. 22 and in practice with the illustrated machine is usually less than one-third of a degree.

Supported on the rod 104 (which is fixed to dresser. slide 105) for both axial and pivotal motions is a dresser housing 112, this housing supporting the outer races of The center C of the round r linear ball bearing units 110. As shown in Fig. 10, the dresser slide has a part received between bifurcations of the housing 112 which extend around the rod 104, so that the housing will move axially along the rod with the dresser slide. A dresser bracket 113, Fig. 11, has a tubular part 114 slidable along axis 115 in a bore in housing 112. The bracket is prevented from turning about axis 115 by a guide pin whose flat faces 120, Figs. 11 and 16, are engaged by guide rollers supported, by the housing. Axis 115 is parallel to the common plane of the axes of rods 103 and 104 but is inclined to these rods at an acute angle equal to the angle between the plane side face 34 and the conical side face of wheel W. The arrangement is such that as the bracket 113 moves along axis 115, the diamond D moving as a unit with the bracket will move across the plane surface 34 of the wheel in a direction radial of wheel axis 33; and as the housing '112 pivots about rod 104' the diamond moving as a unit with it will pass across the wheels tip surface 100. For dressing the round at the juncture of surfaces 34 and 100 the diamond is rotatable with dresser arm 116 about the axis of shaft 117 which is perpendicular to axis 115. The shaft is mounted in bracket 113 on the anti-friction bearings shown in Fig. 12. The dressing operation may be better understood by reference to Fig. 24 where the direction of rod104 is shown at 104". During the first phase of the operation the tool is swung about axis 104" from D to D to thereby dress the tip 100 of the wheel. During the next phase the tool is swung about axis 90 from'l) to D to dress the round on the wheel. Finally the tool is moved rectilinearly along axis 115 from D to D to dress wheel surface 34.

The aforementioned dressing motions of the diamond are all effected by a hydraulically operated actuator contained within the housing 112, Figs. 11 and 17. This actuator comprises a cylinder 121 slidable on a piston 118 and piston rod 119, the latter being secured to the housing. The cylinder is reciprocated by fluid under pressure applied alternately to the left and right chambers thereof, the fluid being conducted to and from the chambers through flexible conduits 132 and 133 which are connected to the piston unit 118, 119, and which com municate with passages through that unit that open re spectively into the left and right cylinder chambers. The cylinder carries a guide member 122 which has a tongue slidable in a guide groove in a part 123 secured to the housing. The cylinder also carries a roller 124, Figs. 11, 12 and 14, which rides on a camsurface 125 on slide 105 and on an adjoining cam surface 126, the latter being formed on a worm wheel 127 that is mounted for rotation on the slide by turning of an adjusting worm 128. This worm has a calibrated head 128 to show the angle, from 0 to 12", that the cam surface 126 makes with the adjacent portion of the cam surface 125. In the 0 position of adjustment, which is the condition shown in full lines in Fig. 14, the surface 126 is parallel to the piston rod 119. The housing is constantly urged about rod 104 by a hydraulically biased plunger 129 which is slidable in a cylinder in the housing and bears upon slide 105, to thereby maintain the roller 124 in contact with the cam surfaces. Fluid pressure is applied to the plunger through a passage 141, Fig. 17. Therefore during initial. motion of the cylinder 121 to the left in Figs. 11 and 17 as a result of fluid entering the left cylinder chamber through conduit 132, Fig. 17, and exhausing from the right chamber through conduit 133, the roller 124 will follow along the inclined portion of cam surface 125, to the right in Fig. 14, causing the housing 112 to pivot on rod 104, carrying. the diamond D across the wheels tip surface 100. Extending through the wall of cylinder 121 intermediate of the ends thereof is a bleed opening 131, whose purpose will be described later.

At the conclusion of this first phase of the dresser motion the member 122 on the cylinder 121 is in abutment with a button 134 on a rack 135, Figs. 11 and 12, which arm bracket 113. The rack 135 meshes with an idler pinion 136, Fig. 13, which is rotatable in the arm bracket 113 and meshes with an idler rack 137 that is slidable on the bracket. Rack 137 meshes with a pinion 138 on the shaft 117 of dresser arm 116. Consequently continuing motion of cylinder 121 ,to the left in Fig. .11 will cause the diamond D to be rotated around the axis of shaft 117 and thereby dress a round or radius on the wheel at the juncture of surfaces 34 and 100 thereof. The radius of this round depends upon the distance to which/the point of the diamond is adjusted from the axis of shaft 117. If the distance is made zero the round will of course be eliminated. A hydraulically biased rack plunger 139 slidable in the dresser arm bracket 113 also meshes with pinion 138, and takes up backlash in the rack and pinion drive train 135, 136, 137, 138 and also holds shoulder 143 of rack 135 in abutment with a nipple 144 on part 114 at all times when the cylinder carried part 122 is out of contact with button 134. During the part of the stroke of cylinder 121 in which the rack 135 is being moved relative to bracket 113, the roller 124 is on a plane part of cam surface 125 that is parallel to rod 119. Accordingly the housing 112 is held against pivotal motion on rod 164.

Hydraulic pressure from passage 141 is also effective upon a piston 147 which, like the nipple 144, is affixed to part 114, for constantly urging the dresser arm bracket 113 to its limit position to the right, in Fig. 11. By means of port 146, a communicating passage 145 in rack 114, and a closure cap 142, the hydraulic pressure from the cylinder containing piston 147 is applied to the rack plunger 139. Upon continued advance of the cylinder 121 far enough for the part 122 to 'abut nipple 144 (the button 134 now having been moved to a position completely within the nipple), the bracket 113 and rack 135 move as a unit with the cylinder. Accordingly the diamond D is traversed across the Wheel face 34 in a direction radial of the wheel. If the cam surface 126 is in its zero position of adjustment there is no rotation of the diamond D about axis of rod 104 during this traverse, and hence the wheel face 34 will be dressed by the diamond as a plane surface perpendicular to wheel axis 33. On the other hand if the surface 126 is inclined, for example to the position shown in broken lines 126' in Fig. 14, then during such traverse the dresser body will be given a motion about the axis of shaft 104 which imparts to the diamond a motion in the direction of wheel axis 33. The result will be that the wheel face 34 will be dressed as a slightly dished or conically concave surface so that the gear tooth surfaces ground thereby will be slightly crowned from end-to end.

At the conclusion of the dressing stroke a pin 148 carried by cylinder 121 abuts the spring-backed actuating stem 149 of a limit switch 151 which is mounted on the body 112. This closes the normally open contacts of the switch for a purpose to be described hereinafter. During reverse motion of the cylinder, effected by connecting conduit 133 to pressure and conduit 132 to exhaust, the diamond D retraces its motions previously described. At the conclusion of the return motion a pin 152 on the cylinder abuts the actuating stem 153 of a limit switch 154, opening the normally closed contacts of the switch. Preferably the pins 148 and 152 are screw-threaded to the cylinder for adjustment relative thereto.

The cylinder 121 controls a piston valve 155 which is slidable in a cylindrical sleeve 156 mounted in the dresser body 1112, the valve controlling the application of fluid pressure to the opposite faces of piston 68 which operates the wheel-advance ratchet mechanism '71, 67. The piston valve 155 is normally urged to the left in Figs. ll and 17, by fluid pressure from passage 141, to a limit position wherein shoulder 157 abuts the sleeve. As the cylinder 121 approaches the end of its return stroke, to

8 the right in Figs. '11 and 17, a button 158 carried by it abuts the valve and moves .it to its limit position to the right.

The dressing operation may be controlled either. manually or automatically in time with the various motions of the machine, such for example by the control system disclosed in aforementioned Patent No. 2,556,402. A manually controlled system, diagrammed in Fig. 17, includes a sump 159, .a pump P for delivering hydraulic fluid from the sump .to pressure passages 141, :a control valve 161 for directing fluid under pressure either to passage 132 or 133 and return flow from this passage through return passages .162 to the sump. In passage 133 are arranged in parallel a throttle valve 163 and a check valve 164. Valve 161 is shifted to the right in Fig. 17 by a solenoid 165 and to .the left by a solenoid 166. These solenoids are controlled by the limit switches 151 and Y154 and a manually operated push-button typeswitch 167.

In the condition of the parts shown in Fig. 17, .a dressing stroke of cylinder 121 has been concluded and pressure from pump P is applied through passage 141, valve 161 and passage 132 to the left chamber of the cylinder, while the right chamber thereof is on exhaust via throttle 163 (check valve 164 being closed), passage 133, valve 161 and return line 162 to the sump. Valve is held in its left limit position by pressure applied through passage 141, so that piston 68 is held in its reset position by pressure applied through passage 141, passage 168 in valve 155 and passage 169. The right chamber of cylinder 69 is on exhaust via passage 171, valve 155 and return passage 162.

It will be understood that the wheel dressing operation is carried out when the wheels are disengaged from the Work but are being rotated by their motors 47. To effect a dressing operation the switch 167 is momentarily closed establishing an electric circuit from lead L1 to lead Lz through now closed limit switch 151 and the winding of solenoid 165. This solenoid shifts valve 161 to the right so that pressure from line 141 is applied through passage 133 and now open check valve 164 to the right chamber of the cylinder 121, effecting a rapid return or reset stroke thereof. During this stroke some fluid escapes to the sump from bleed 131, but not enough to affect the rapid reset operation. Toward the end of this stroke the button 158 abuts and shifts valve 155 to the right, reversing the pressure and exhaust connections to cylinder 69 and thereby causing the wheel advance stroke of piston 68. At the conclusion of the dresser reset stroke of cylinder .121 the limit switch 154 is closed, establishing a circuit from L1 to L2 through solenoid 166 which acts to shift valve 161 to the left. Solenoid 165 is of course deenergized at the initiation of the reset stroke of cylinder 121 because of the opening of limit switch 151 but the valve 161 has been shifted to the right before the reset motion starts, and it remains in this position until solenoid 166 is subsequently energized. Upon valve 161 being shifted to the left the dressing stroke of cylinder 121 takes place.

During the initial part of this stroke the button 158 moves away from valve 15.5, allowing pressure in line 141 to shift the valve to its left limit position, thereby causing the reset stroke of piston 63. The fore part of the dressing stroke of cylinder 121 is slow because of the restriction in line 133 imposed by throttle valve 163 and because of the loss of fluid from the right chamber of the cylinder through the bleed opening 131 which discharges into return passage 162. During the first part of the dressing stroke the roller 124 cooperates with cam 125 to rock the dresser body on shaft 164 to pass the tool D over the tip surface 109 of the now rotating wheel 47, dressing an amount of stock therefrom which depends upon the length of the preceding stroke of piston 68 as determined by adjustable stop plate 78. At the conclusion of this first part of the dressing strokeof cylinder 121 the part h 122 abuts button 134 and acts through the rack and pinion members 135, 136, 137, 138 to rotate shaft .117 and the tool D carried thereby, to dress the radius on the wheel at the juncture of its surfaces 34 and 100. At the conclusion of this second part of its dressing stroke, when the part 122 abuts nipple 144, the piston covers the bleed opening 131 and hence proceeds at a slower rate during the third part of the dressing operation in which the tool D traverses the side surface 34 of the wheel. By this slow-down it is possible to approximately equalize the rate of travel of the tool over the tip, the round and the side surfaces of the wheel.

, The system and operation above described applies to each of the two dressers and wheel feed mechanisms, each of them having its own control valves 155 and 161, although both may utilize the same sump 159 and pump P. The solenoids for operating the valve 161 of the upper dresser are designated in Fig. 17 as 165 and 166', these being controlled by the switch 167 and by the limit switches of the second dresser, designated 151 and 154. Consequently the operation of both dressers is initiated by. closing of the single switch 167.

The various external moving parts of the dresser are connected by bellows-like seals 172 which prevent abrasive material getting on the working surfaces. These seals also enable the entire interior of the dresser body to serve as a part of the fluid return system which in the diagram Fig. 17 is indicated as comprising the conduit 162.

The operation of the dresser may be reversed, if desired, to cause dressing to take place during motion of the cylinder to the right instead of to the left in Figs. 11 and 17. This may be accomplished by reversing the hydraulic connections of control valve 161 to the cylinder and by rearranging the piston valve 155 so that it is shifted by the cylinder as the latter moves to and from its limit position to the left in Figs. 11 and 17. The bleed opening 131 is also relocated. As the diameters of the Wheels W are reduced by the operation of the pistons 68, ratchet means 67, 71 and screws 54, and by the concomitant operation of the dressers, the peripheral wheel speed is maintained substantially constant by means shown in Figs. 18 and 19 including a rheostat 173 supported in a housing 174 on the upper vertical slide 53. Mounted on the rotatable actuating shaft 175 of the rheostat is a gear sector 176 meshing with rack teeth 177 on a rod 178. The rod is slidable in housing 174 inthe direction of its length, parallel to the wheel feed screw 54, and is connected by a fitting 179 to the housing of upper motor 47. Accordingly as the wheel diameter decreases the rheostat is turned in a direction to decrease its resistance, which through suitable means increases the speed of the wheel motors. When the wheels reach a predetermined minimum diameter, and hence are no longer usable, gear sector 176 abuts the actuating stem 181 of a limit switch 182 mounted in the bracket, to close the contacts of the switch. The latter is connected in series in an electrical circuit with a suitable audible or visual signal (not shown) to warn the machine operator of the wheels condition of wear.

The specific means whereby the rheostat 173 controls the speed of wheel motors 47 is not a part of the present invention. However one suitable arrangement for this purpose is shown diagrammatically in Fig. 20 in which an alternating current motor 183, operated from a three phase source L1, L2, L3, drives a frequency changer 184, being connected thereto by an eddy-current clutch 185 whose field coils are connected in series with the rheostat 173 in circuit with a source of direct current designated D. C.; and the wheel motors 47 being operated by the output current of the frequency changer. With this arrangement the speed of the motors 47, which is proportional to the frequency of the current delivered by the frequency changer 184, is increased as the field strength arsenic 16 of the clutch is increased as result of decrease it the resistance of the rheostat 173.

Having now described the preferred embodiment of our invention, what we claim is: l

1. A dresser mechanism comprising a support, a lionsing pivoted to the support, a bracket slidable on the housing, an arm carrying a dressing tool and rotatable on the bracket about an axis inclined to the pivot axis, and means operable during operation of the mechanism to successively pivot the housing on the support, turn the arm on the bracket and slide the bracket on the housing.

2. A mechanism according to claim 1 in which said means comprises an actuator movable in the housing in the direction in which the bracket is slidable, cam means effective between the actuator and the support to effect the pivot motion during one phase of the motion of the actuator, means operable by the actuator during another phase of said motion to turn the arm on the bracket, and the bracket being slidable on the housing by the actuator during still another phase of said motion.

3. A mechanism according to claim 2 in which the means to turn the arm on the bracket comprises a rack slidable in the bracket in the direction in which the bracket is slidable, the actuator being so arranged that during its stroke in one direction it first slides the rack relative to the bracket, to effect turning of the arm, and then slides the rack and the bracket as a unit relative to the housing.

4. A mechanism according to claim 2 in which the cam means comprises a cam and a cam follower, a part of the cam being inclined to the direction of actuator motion and another part of the cam being substantially parallel to said direction, the follower engaging the inclined part of the cam to effect the pivot motion of the housing on the support and engaging said other part of the cam during the other phases of the motion of the actuator.

5. A mechanism according to claim 4 in which said other part of the cam is adjustable into inclined relation to the direction of actuator motion, for causing the housing to pivot on the support while the bracket slides on the housing.

6. A mechanism for dressing a conical abrasive wheel comprising a support, a housing pivoted to the support about an axis at least approximately parallel to an element of the conical side surface of the wheel, a bracket slidable on the housing in the direction of a line that is perpendicular to the wheel axis and is coplanar with the wheel axis and said element, an arm carrying a dressing element and rotatable in the bracket about an axis perpendicular to said line, an actuator movable in the housing in the direction of said line, cam means effective between the actuator and the support to pivot the housing on the support during one phase of the motion of the actuator to cause the tool to dress a peripheral tip surface on the wheel adjacent the conical. surface thereof, means operable by the actuator during another phase of said motion to rotate the arm in the bracket to cause the tool to dress a round on the wheel at the juncture of said tipsurface and the side surface opposite the conical side surface, and the bracket being slidable: on the housing by the actuator during still another phase of said motion to cause the tool to dress said opposite side surface of the wheel.

7. A dresser mechanism comprising a support, a housing pivoted to the support, a dresser carrying bracket slidable on the housing, a pair of cams on the support, an actuator slidable on the housing in the same direction as the bracket, the actuator being arranged to slide free of the bracket during, one part of its stroke and to move the bracket therewith during another part of its'strok'e; a cam follower on the actuator engageable with one cam during'said one part of the stroke and with the other cam during said other part of the stroke, said one cam being ,1 1 inclined to said direction to cause pivotal motion of the housing on the support during said one part of the stroke, and the other cam being adjustable on the support and in one position of such adjustment being parallel to said direction.

8. A dresser mechanism comprising a support, a housing pivoted to the support, a bracket slidable on the housing, an arm carrying a dressing tool and rotatable on the bracket about an axis inclined to the pivot axis, a rack slidable on the bracket in substantially the direction that the bracket is slidable, said rack being connected to the arm for rotating the latter, an actuator slidable in the housing in said direction and having a cam follower thereon, the actuator being free of the bracket and the rack during one part of its stroke and being arranged to move the rack therewith during another part of said stroke and to move both the rack and the bracket therewith during still another part of said stroke, a first cam on the support engaged by the cam follower during said one part and said another part of said stroke, said first cam being shaped to effect pivotal motion of the housing on the support during said one part of said stroke and to hold the housing against pivotal motion during said another part of said stroke, and a second cam on the support engaged by the cam follower during said still another part of said stroke, said second cam being adjustable on the support into either parallel or inclined relation to said direction for respectively holding the housing against pivoting or causing it to pivot during said still another part of said stroke.

9. A grinder comprising a support, a wheel head having a conical abrasive wheel journalled for rotation thereon, the wheel head being movable rectilinearly on the support at least approximately in the direction of an element of the conical surface of the wheel, a dresser for the wheel mounted for rectilinear motion on the head in at least approximately the direction of another element of the conical surface of the wheel, and means for effecting the two motions in predetermined ratio to each other.

10. A grinder according to claim 9 in which said means for effecting the two motions comprises a cam and cam follower for causing the dresser to move on the head in response to motion of the head on the support, one of the cams and cam followers being movable with head and the other being movable with the dresser.

11. A grinder according to claim 9 in which the dresser is mounted for said rectilinear motion upon a member that is adjustable relative to the Wheel head about an axis perpendicular to the wheel axis and approximately tangent to the periphery of the wheel, to vary the direction of said rectilinear motion relative to the direction of said another element of the conical surface of the wheel.

12. A grinder according to claim 9 in which said means, for effecting the two motions in predetermined ratio to each other, is adjustable to vary said predetermined ratio.

13. A grinder for gears and the like comprising a work support and a tool support, a wheel head on the tool support having an abrasive wheel journalled for rotation thereon, said wheel having side and tip surfaces respectively for grinding tooth side and root surfaces of a workpiece on the work support, means to feed said head rectilinearly on the tool support in a direction inclined at a predetermined angle to the axis of rotation'of'the Wheel to compensate for reduction in wheel diameter, a dresser for said wheel surfaces mounted for feed motion on said head in a direction inclined to said axis at an angle differing from said predetermined angle, and means operable concomitantly with the head feed means to effect such feed motion of the dresser at a rate different from the rate of feed of the head.

14. A grinder for gears and the like comprising a work support and a tool support, a wheel head on the tool support having an abrasive wheel journalled for rotation thereon, said wheel having side and tip surfaces respectively for grinding tooth side and root surfaces of a workpiece on the work support, means to feed said head rectilinearly on the tool support in a direction inclined at a predetermined angle to the axis of rotation of the wheel to compensate for reduction in wheel diameter, a dresser for said wheel surfaces and guide means mounting the same for feed motion relative to the head, said guide means being adjustable whereby the direction of dresser feed motion may be inclined to said axis at an angle different from said predetermined angle, and dresser feed means operable concomitantly with the head feed means to effect such feed motion of the dresser at a rate proportionate to the rate of feed of the head, the dresser feed means including means adjustable to vary the dresser feed rate relative to the head feed rate.

15. A grinder for gears and the like comprising a work support and a tool support, a wheel head on the tool support having an abrasive wheel journaled for rotation thereon, said wheel having side and tip surfaces respectively for grinding tooth side and root surfaces of a workpiece on the work support, means to feed said head rectilinearly on the tool support in a direction inclined at a predetermined angle to the axis of rotation of the wheel to compensate for reduction in wheel diameter, a dresser for said wheel surfaces and guide means mounting the same for feed motion relative to the head, said guide means being adjustable whereby the direction of dresser feed motion may be inclined to said axis at an angle different from said predetermined angle, and dresser feed means operable concomitantly with the head feed means to effect such feed motion of the dresser at a rate proportionate to the rate of feed of the head, the dresser feed means including means adjustable to vary the dresser feed rate relative to the head feed rate, the adjustments of the guide means and of the relative feed rates enabling the dresser to be maintained in a relative position wherein it will (a) dress the side surface of the wheel so that an element thereof, which element lies in a plane containing the wheel axis and is parallel to the direction of feed of the head, has a constant positional relationship to the tool support, and (b) dress the tip surface of the wheel to have a constant depthwise relationship to the ends of the tooth spaces being ground on the workpiece.

16. A grinder for gears and the like comprising a work support and a tool support of which one is a rotatable cradle, a wheel head on the tool support and having an abrasive wheel journaled for rotation thereon, said wheel having side and tip surfaces respectively for grinding the tooth side and root surfaces of a workpiece on the work support, the axis of rotation of the Wheel being at a predetermined angle to the cradle axis, means to feed said head on the tool support in the direction of the cradle axis to compensate for reduction in wheel diameter, a dresser for said wheel surfaces mounted for feed motion on the head in a direction inclined to said axis at an angle differing from said predetermined angle, and means operable concomitantly with the head feed means to effect such feed motion of the dresser at a rate different from the rate of feed of the head.

17. A grinder for gears and the like comprising a work support and a tool support of which one is a rotatable cradle, a Wheel head on the tool support and having an abrasive wheel journaled for rotation thereon, said wheel having side and tip surfaces respectively for grinding the tooth side and root surfaces of a workpiece on the work support, the axis of rotation of the wheel being at a predetermined angle to the cradle axis, means to feed said head on the tool support in the direction of the cradle axis to compensate for reduction in wheel diameter, a dresser for said wheel surfaces and guide means mounting the same for feed motion relative to the head, said guide means being adjustable whereby the direction of dresser feed motion may be inclined to said axis at an angle different from said predetermined angle, and dresser r 13 feed means operable concomitantly with the head feed means to etfect such feed motion of the dresser at a rate proportionate to the rate of feed of the head, the dresser feed means including means adjustable to vary the dresser feed rate relative to the head feed rate.

18. A grinder for gears and the like comprising a work support and a tool support of which one is a rotatable cradle, a Wheel hea d on the tool support and having an abrasive wheel journaled for rotation thereon, said wheel having side and tip surfaces respectively for grinding the tooth side and root surfaces of a workpiece on the work support, the axis of rotation of the Wheel being at a predetermined angle to the cradle axis, means to feed said head on the tool support in the direction of the cradle axis to compensate for reduction in wheel diameter, a dresser for said wheel surfaces mounted for feed motion on the head in a direction inclined to said axis at an angle differing from said predetermined angle, and means operable concomitantly with the head feed means to effect such feed motion of the dresser at a rate different from the rate of feed of the head, the adjustments of the guide means and of the relative feed rates enabling the dresser to be automatically maintained in a relative position wherein it will (a) dress the side surface of the wheel so that an element thereof, which element lies in a plane parallel to the cradle axis and containing the wheel axis, has a constant positional relationship to the tool support, and ([2) dress the tip surface of the wheel to have a constant depthwise relationship to the ends of the tooth spaces being ground on the work.

19. A grinder comprising a support, a wheel head having a conical abrasive wheel journaled for rotation thereon, the wheel head being movable rectilinearly on the support in the direction of an element of the conical surface of the Wheel, a slide movable rectilinearly on the head in at least approximately the direction of another ele ment of the conical surface of the wheel, feed means for simultaneously effecting motions of the head on the support and the slide on the head, a dresser housing pivoted to the support upon an axis extending in the direction in which the slide is movable on the head, a bracket slidable on the housing in the direction of a line perpendicular to the Wheel axis and co-planar with the wheel axis and said other element of the conical surface, an arm carrying a dressing tool and rotatable on the bracket about an axis perpendicular to said line, actuating means to successively (a) pivot the housing on the support to move the tool across the tip surface of the Wheel, (b) turn the arm on the bracket and (c) slide the bracket on the housing to move the tool across a surface of the wheel at least approximately perpendicular to the wheel axis.

20. A grinder comprising a support, a wheel head having a conical abrasive wheel journaled for rotation thereon, the wheel head being movable rectilinearly on the support in the direction of an element of the conical surface of the wheel, a slide movable rectilinearly on the head in at least approximately the direction of another element of the conical surface of the Wheel, feed means for simultaneously effecting motions on the head on the support and the slide on the head, a dresser housing pivoted to the support upon an axis extending in the direction in which the slide is movable on the head, a bracket slidable on the housing in the direction of a line perpendicular to the wheel axis and coplanar with the wheel axis and said other element of the conical surface, an arm carrying a dressing tool and rotatable on the bracket about an axis perpendicular to said line, actuating means to successively pivot the housing on the support to move the tool across the tip surface of the wheel, turn the arm on the bracket and slide the bracket on the housing to move the tool across a surface of the wheel at least approximately perpendicular to the Wheel axis, said feed means comprising a ratchet mechanism to elfect step-by-step motions of the head and the slide, the actuating means comprising a reciprocable member, and means operative to first effect a. reset stroke of said reciprocating member, then effect an advance of the ratchet mechanism, and then effect an operating stroke of the reciprocating member and a reset of the ratchet mechanism.

21. The method of dressing on an abrasive wheel two angularly related profiles and the round connecting them, while maintaining the dressing tool at substantially the same inclination to the surface being dressed, which comprises in successive steps moving the tool rectilinearly across the surface of the Wheel of one of said profiles, rotating the tool over the round about an axis which is at least approximately perpendicular to the direction of the rectilinear movement and which passes through the center of the round, and moving the tool across the surface of the other profile about an axis which is at least approximately perpendicular to the first-mentioned axis.

22. A grinder comprising a support, a wheel head having a conical abrasive wheel journaled for rotation thereon, the wheel head being movable rectilinearly on the support in at least approximately the direction of an element of the conical surface of the wheel, a dresser movable rectilinearly on the head in the direction of another element of the conical surface of the wheel, feed means for simultaneously eifecting movement of the head on the support and movement of the dresser on the head, said dresser being adapted to, dress a tip surface of the wheel adjacent said conical surface and a surface adjacent said tip surface which is at least approximately perpendicular to the wheel axis, a motor for driving the Wheel, and speed control means for the motor operable by said feed means for increasing the speed of the motor as the diameter of the wheel is reduced.

References Cited in the file of this patent UNlTED STATES PATENTS 1,100,525 Brown June 16, 1914 2,056,871 Silven Oct. 6, 1936 2,092,895 Stevens Sept. 14, 1937 2,162,038 Trible June 13, 1939 2,287,449 Price June 23, 1942 2,302,304 Elberty Nov. 17, 1942 2,310,977 Mathys Feb. 16, 1943 2,566,402 Critchley Sept. 4, 1951 2,587,261 Wildhaber Feb. 26, 1952

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