US1971138A

US1971138A - Grinding machine

Info

Publication number: US1971138A
Application number: US658745A
Authority: US
Inventors: Waldo J Guild
Original assignee: Heald Machine Co
Current assignee: Heald Machine Co
Priority date: 1933-02-27
Filing date: 1933-02-27
Publication date: 1934-08-21
Anticipated expiration: 1951-08-21

Description

Aug. 21, 1934. w J GUlLD 1,971,138

GRINDING MACHINE Filed Feb. 27, 1933 3 Sheets-Sheet l gwwmtoz a wa do 3. Guild.

9 2; %MZMW Aug. 21, 1934. w. J. GUILD GRINDING MACHINE Filed Feb. 27, 1933 3 Sheets-Sheet 2 VII Aug. 21, 1934. w, J. GUlLD 1,971,138

GRINDING MACHINE Filed Feb. 27, 1933 5 Sheets-Sheet 3 J: \Uoldo I. Guilc Patented Aug. 21, 1934 UNITED STATES PATENT; DFFICE GRINDING MACHINE Application February 27, 1933, Serial No. 658,745

21 Claims.

The present invention relates to grinding machines and particularly to a crossfeed mechanism therefor by which to compensate for the reduction in diameter of the grinding wheel as a result of attrition and dressing operations thereon.

In the patent to Guild, the present inventor, No. 1,682,672 and in the patent to Taylor No. 1,682,673, both granted August 28, 1928, the crossfeed mechanism, by its rotation, controls the grinding operation and, thus, during successive grinding operations, the reduction in size of the grinding wheel must be compensated for in order that each successive workpiece may be reduced to the same predetermined size. In these patents, the compensatory mechanism procures a compensatory movement of the grinding wheel which is always uniform regardless of the actual reduction in the size of the wheel and accordingly each compensation must be at least as great as the greatest amount of wear which occurs during any grinding operation.

The patent to Guild, the present inventor, and Burns No. 1,830,358, granted November 3, 1931,

discloses a grinding machine in which the roughgrinding operation on the workpiece is under the control of the crossfeed mechanism, as in the above noted Guild Patent No. 1,682,672, at which time a dressing operation may be automatically performed on the grinding wheel, and thereafter the finished size of the workpiece is determined by a gage mechanism of the type disclosed, for example, in the Kempton and Gallimore Patent No. 1,731,719, granted October 15, 1929 or in the earlier patent to Conradson, Kempton and Gallimore No. 1,534,302, granted April 21, 1925.

Since the completed size of the workpiece is determined by a gage mechanism in this Guild and Burns Patent No. 1,830,358, the compensatory movement of the grinding wheel between successive grinding operations must necessarily correspond substantially to the actual reduction in size of the grinding wheel, with sufiicient additional compensation to permit the dressing tool to engage with the grinding wheel during the successive grinding operation, such compensation being, therefore, variable in accordance with the variation in the wear on the wheel.

It is desirable to provide a single crossfeed mechanism, which is applicable not only to the above cited Guild and Taylor patents in which a uniform compensatory movement is procured between successive grinding operations, but which is also applicable to the Guild and Burns patent above cited in-which the compensatory movement is variable in accordance with the actual wear on the wheel. It is, accordingly, the principal object of the present invention to provide a crossfeed mechanism which is applicable to both of these types of machines.

According to the present invention, the crossfeed mechanism is arranged to procure either a uniform compensatory movement when used in connection with grinding machine instrumentalities of the type shown in the above cited Guild and Taylor patents or a variable compensatory movement when used with grinding machine instrumentalities of the type disclosed in the above cited Guild and Burns patent. In prior crossfeed mechanisms for use in connection with machines of the latter type, it has been customary to provide a slip ring arrangement for controlling the compensatory movement, and the present invention is arranged to dispense with the slip ring type of compensation, and to provide a positive connection which is not subject to the objectionable features of the slip ring.

Other and further objects and advantages of the invention will appear from the following detailed description taken in connection with the accompanying drawings in which:

Fig. 1 is a front elevation of a machine embodying the invention.

Fig. 2 is a fragmentary elevation of the dog bar and associated parts by which the reciprocatory movements of the workpiece relative to the grinding wheel are procured.

Fig. 3 is an elevation of the crossfeed mechanism, with the cover plate thereof removed.

Fig. 4 is a vertical section of the crossfeed mechanism substantially along the line 4-4 of Fig. 3.

Fig. 5 is a vertical section showing the feed pawls substantially along the line 55 of Fig. 4.

Fig. 6 is a vertical section along the line 6-6 of Fig. 5..

Fig. 7 is a fluid pressure diagram.

Fig. 8 is a wiring diagram.

Fig. 9 is a modified wiring diagram, when the machine is operating partly under the control of a gage mechanism.

Like reference characters refer to like parts in the different figures.

Referring first to Fig. 1, the machine provides the usual reciprocatory table 1, provided in an internal grinding machine; and either the grinding wheel or the work to be ground may be carried on said table, the reciprocations of the latter operating in either case to produce a relative translatory movement between said grinding wheel and the workpiece. In the construction shown, the table 1 supports and carries a workhead 2, and the wheelhead 3 is mounted on a bridge 4 which spans the slideways, not shown, provided by the base of the machine for the movements of the table 1. The grinding wheel 5 is carried on a spindle 6 journaled in the wheelhead 3, and the spindle is rotated in any suitable manner for a rotation of the grinding wheel. The workpiece, which is not shown, is held within a suitable chuck '7 carried by the workhead and also suitably rotated but desirably at a slower speed than the grinding wheel.

The reciprocations of the table 1 which cause the rotating grinding wheel 5 to make the required traverse of the rotating workpiece are imparted in any well known manner, as by the use of the fluid pressure controlling and reversing mechanism described in United States Letters Patent No. 1,582,468, granted April 2'7, 1926 to Heald and Guild. It is suflicient to note for the purpose of the present application that the driving means employed for the reciprocations of the table 1 procure the reversal of said table at each end of the normal working stroke by the use of spaced

adjustable dogs

8 and 10 carried by the table and adapted, alternately, to engage and move a reversing member 11. The latter, during the grind ing operation when the workpiece is moving back and forth over the grinding wheel, is situated between the two

dogs

8 and 10, and in a position to be struck alternately by said dogs, and by its consequent movement first in one direction and then in the other, effects the reversal of the movements of the table 1.

The fluid pressure mechanism for actuating the carriage is shown in Fig. '7. In this figure, fluid under pressure is supplied by a pump 12, the pressure side of which is connected by a conduit 13 to a channel 14 in a casing 15 in which a reversing valve 16 is positioned. The latter is connected to the reversing member 11 for movement thereby. Movement of said valve 16 alternately directs fluid under pressure through

conduits

17 and 18 to the left and right hand ends respectively of a cylinder 20 in which a piston, not shown, is slidable. The latter is connected by a piston rod 21 to the table 1 for movement of the table in response to movement of the piston within the cylinder. As fluid under pressure is admitted to one end of the cylinder 20, fluid from the opposite end is allowed to exhaust through an exhaust channel 22 in the casing 15.

The crossfeed movement between the workpiece and the grinding wheel is obtained by movement of the wheelhead 3 transversely of the bridge 4 and in response to the reciprocations of the carriage, as will hereinafter appear. The wheelhead is mounted on a cross-slide, not shown, and the movement thereof is obtained by rotation of a crossfeed screw 23, Fig. 3, which engages an internally threaded portion of the cross-slide. The crossfeed screw 23 carries a gear 24 in mesh with a pinion 25 rotatably mounted on a shaft 26, the latter being secured against rotation in a casing 27 for the crossfeed mechanism. Said pinion 25 during the crossfeed movement of the table, is rotated in unison with a ratchet wheel 28, which latter is actuated in response to the reciprocations of the table; the mechanism by which the pinion 25 is connected to the ratchet wheel will be disclosed hereinafter as this mechanism forms a part of the present invention. The rotation of the pinion 25 procures, through rotation of the crossfeed screw 23, a crossfeed movement of the grinding wheel transversely of the machine to cause said wheel to out successively deeper and deeper into the work, the extent of the grinding operation being controlled by said crossfeed movement .as will hereinafter appear.

Referring now to Fig. 3, in which is shown the mechanism for procuring the crossfeed movement, an arm 30 is pivotally mounted on the shaft 26 and carries at its outer end .a pin 31 on which a bell crank lever 32 is pivotally mounted. One arm of said lever carries a pawl 33 which is pivotally mounted on a stud 34 in the end of said arm, said pawl being held against rotation by a pin 35. This structure provides for use selectively of any one of a plurality of points on said pawl member. A second arm 36 of the lever 32 is engageable with an adjustable stop 3'7 in a lug 38 integral with the arm 30 and said stop is arranged to support the bell crank lever against counterclockwise rotation on the pin 31. The arm 36 of the bell crank lever 32 also engages an abutment 40 carried by one arm 41 of a lever 42 pivotally mounted on a stud 43 secured to the casing 2'7, said lever being normally held against movement so that the abutment forms a limiting stop for counterclockwise movement of the arm 30.

As above stated, the pawl for advancing the ratchet wheel 28 is actuated in response to the movements of the table. To this end, as shown in Fig. 3, the arm 44 of the bell crank lever 32 is in a position for engagement with a roller 45 on the end of the an arm 46 of a lever 4'7 pivotally mounted on the same stud 43 that supports the lever 42. The other arm 48 of the lever 47 is connected by a link 50 to an arm 51 of a lever 52 joumaled on a stud 53 on the housing 2'7. The opposite end of the lever 52 carries a roller 54 which is in a position for engagement with a cam, not shown, on the reciprocating carriage, said cam engaging beneath and elevating said roller during each reciprocation of the carriage. Elevation of said roller procures a corresponding elevation of the roller 45 into engagement with the arm 44 of the bell crank lever 32, thereby rocking said bell crank lever about the pin 31 to bring the pawl member 33 into engagement with the ratchet wheel 28. Continued elevation of the arm 44 procures turning movement of the arm 30 while the pawl 33 is in engagement with the ratchet wheel, thereby causing a clockwise advance of the ratchet wheel. A pin 55 in the casing 27 prevents excessive counterclockwise movement of the levers 4'7 and 52, thereby supporting the roller 54 in proper position for engagement with the cam on the carriage. The roller 45 is thus given a predetermined oscillatory movement during each reciprocation of the carriage.

Although the roller 45 has a predetermined oscillationv during each reciprocation of the carriage, the resultant turning movement of the ratchet 28 is varied by adjusting the position of the stop or abutment 40. Referring again to Fig. 3, the opposite end 42a of the lever 42 engages one arm of a bell crank lever 56 against which the end 42a is held by a spring 57. One end of the spring 5'7 engages the lever 42 and the other end of said spring is suitably connected to a part of the casing 2'7. The abutment 46 thus limits the downward swinging movement of the arm 30 and also of the pawl carrying lever 32, thereby determining the extent of the advance of the crossfeed slide for each reciprocation of the table.

The bell crank lever 56, which is normally sta-. tionary, is arranged for adjustment during the grinding operation for diminishing the rate or crossfeed movement during the latter part of the grinding operation when the workpiece is reduced substantially tothe desired size. To this end, the lever 56 is mounted for oscillation on a pin 58 supported by the housing 27, and said lever 56 is normally held against clockwise rotation by an eccentric disc 59 secured to a pin 60 which is manually adjustable in the lionsing 27, said eccentric disc engaging one arm of the lever 56. During the clockwise advance of the ratchet wheel 28 during the crossfeed movement, a cam 61 rotatable as a unit with the ratchet wheel, engages'a pin 62 mounted on one of the arms of the lever 56 to procure a slight counterclockwise rotation of said lever and a corresponding elevation of the abutment 40, thus limiting the oscillation of the arm 30 and thereby decreasing the extent to which the arm 30 is elevated by the roller 45 during each reciprocation of the table and thus reducing the rate of crossfeed movement.

The grinding operation, as above stated,'is under the control of the crossfeed movement and the mechanism for this purpose corresponds substantially to that described in the above cited Guild Patent No. 1,682,672; it is sufficient to note for the purposes of the present application that, during the crossfeed movement, a cam 63, which is rotatable as a unit with the ratchet wheel 28, passes under and elevates an adjustable screw 64 carried by an oscillatory lever 65 journaled on the above-mentioned stud 53. Said lever 65 has spaced contacts 66 and 67 for engagement, successively, with

contacts

68 and 70 carried, respectively, by

arms

71 and 72 pivotally mounted on the stud 53. The lever 65 is held resiliently in operative position by a spring 73 which engages the end of an arm 74 integral with said lever 65 to hold said arm 74 in engagement with a positioning cam 75 supported by the housing 27. The

arms

71 and 72 are suitably held in the position shown, being resiliently supported against counterclockwise movement. Engagement of the

contacts

66 and 68 procures an extended movement of the table to permit a dressing operation to be performed on the grinding wheel, and subsequent engagement of the contacts 67 and 70 procures a second separation of the workpiece from the grinding wheel when the workpiece has reached the desired finished size.

Referring now to Fig. 8, it is sufllcient to note for the-purposes of the present application that the contact 66 is grounded at 76, and the contact 68 is connected by a lead 77 to one terminal of an electromagnet 78, the other terminal of which is connected by a lead 80 to one contact 81 of a switch 82 onwthe front of the machine. The other contact 83 of the switch is connected by a lead 84 to one terminal of a suitable source of power, such as a generator 85, the other terminal of which is groundedat 86. The contacts of the switch 82 are normally connected by, a switch member 87 pivotally mounted on the front of the machine. Engagement of the

contacts

66 and 68 completes a circuit through, and energizes, the electromagnet 78 to procure attraction of its armature 88, and corresponding elevation of an integral upwardly extending lever arm 90, the latter being pivotally mounted on a pin or stud 91 on the front of the machine.

Elevation of the lever arm 90 procures an extended movement of the table to the left by a sliding movement of the reversing dog 10 to the right along the front of the table, which movement prevents the normal rocking movement of the reversing member 11. The extended movement carries a dressing tool 92', Fig. 1, past the grinding wheel. and the table is subsequently reversed to return the grinding wheel and workpiece to operative relation. The reversing dog 10, Fig. 2, is carried by a block 93 slidably mount ed on the front of the table, and is normally held in spaced relation to a similar block 94, secured against movement on the table, by a latch 95 pivotally mounted on the block 94 and engaging a shoulder on the block 93. .Elevation of the lever arm 90 .raises the free end ofthe latch 95 away from the shoulder to permit movement of the block 93 to the right, so that the table moves to the left beyond its normal or operative position.

During this movement, the dressing tool 92, which is of any well-known type, is moved into operative dressing position by any suitable mechanism such as that shown in the patent to Heald and Guild No. 1,779,094, granted October 21, 1930,

in which the movement of the dressing tool is procured by fluid under pressure under the control of and in responseto movement of a depending lever arm 96 integral with the armature 88 and the lever arm 90. Said lever arm 96 is suitably connected to a valve, not shown, and movement of said valve procures movement of said dressing tool into operative position.

After the dressing tool has been carried past the grinding wheel during movement of the table to the left, said movement is reversed by engagement of the sliding block 93 with the stationary block 94, thereby rocking the reversing member 11. The grinding wheel and workpiece are then returned to operative position by movement of the table to the right, and the sliding block 93 is restored to normal position by engagement of said block with a resetting member 97, Fig. 2, mounted on the base of the machine and resiliently urged upwardly for engagement with said block. Repetition of the dressing operation is prevented by rocking of the switch plate 87 to break the connection between the

contacts

81 and 88, which rocking movement is effected by a depending lug 93 carried by the block 94 on the table,

said lug engaging a projection 100 on a member 101 connected to the switch plate. The switch plate 87 is rocked by the depending lug 98 at the end of the movement of the carriage to the left for the dressing operation, thereby procuring deenergization of the electromagnet 78 so that the lever arm 90 returns to the normal position. As the carriage is returned to the right, to bring the grinding wheel and the workpiece again into operative position, a roll 102 carried by the support for the dressing tool engages a cam 103 on the bridge 4, the latter operating to move the dressing tool positively into its upper inoperative position of Fig. 1.

After the grinding wheel and workpiece have been returned to operative position, following the dressing operation, grinding continues on the workpiece until the cam 63 has brought the contacts 67 and 70 into engagement, when the workpiece-is withdrawn from the grinding wheel by an extended movement of the table to the left andthe latter is brought to rest. Referring now to Fig. 8, the contact 67 is grounded at 76 above noted, and the contact 70 is connected by a lead 104 to one terminal of an electromagnet 105, the other terminal of which is connected by a lead 106 to one side of the generator 86. When the contacts 67 and 70 are in engagement, the elec-: tromagnet 105' is energized, causing attraction of the armature 107 and corresponding elevation of a lever arm 108 integral therewith. The lever arm and armature are pivotally mounted on the front of the machine on the same shaft 91 that provides a pivotal support for the armature 88. Elevation of the lever arm 108 procures an extended movement of the table to the left by elevation of the reversing dog 10, which is pivotally mounted on the block 93. Elevation of the dog 10 allows the table to move beyond its normalstroke to the left, without actuating the reversing member 11, and the table is brought to rest in the inoperative position 01 Fig. 1 by any suitable mechanism, not shown.

The above described structure does not, of itself, comprise the present invention; the latter involves the attainment, in connection with grinding machine instrumentalities of the general type above described, of the novel results above set forth. The above described structure, without a compensation for reduction in size of the grinding wheel, will not reduce successive workpieces all to the same predetermined size, and it becomes necessary to provide a form of compensatory mechanism for adjusting the relative angular position between the pinion 25 and the cam 63 by which the grinding operation is controlled. Thus, with a compensatory movement, the crossfeed slide will be advanced, during each successive grinding operation, beyond its advance in the preceding grinding operation a distance corresponding substantially to the reduction in diameter of the grinding wheel. The present invention is thus arranged to provide a suitable compensatory movement so that each successive workpiece may be reduced to the same desired size, independently of the change in size of the grinding wheel.

Referring now to Figs. 3 and 4, the ratchet wheel 28 is connected as by bolts 110 to an annular member 111 journaled on the shaft 26, and said member 111 has an integral sleeve 112 to which a hand wheel 113 is secured as by a key 114. The annular member 111 provides spaced

studs

115 and 116 secured to said member by

nuts

117 and 118 andsaid studs provide pivotal supports for

pawls

120 and 121, Fig. 5,

respectively. Said pawls are arranged to engage a ratchet wheel 122 integral with the pinion 25, and are normally maintained resiliently in engagement with said ratchet wheel by a spring 123. The pawl 121 procures clockwise turning of the ratchet wheel 122 and the pawl 120 procures counterclockwise turning of the ratchet wheel 122 in response to corresponding rotation of the ratchet wheel 28 so that both of said ratchet wheels normally rotate together as a unit.

During the crossfeed movement of the grinding wheel, the ratchet wheel 28 is advanced clockwise, and the pawl 121, which is advanced therewith, procures a clockwise advance of the ratchet wheel 122 in unison with said ratchet wheel 28. As the grinding operation continues, a pin 124 on the pawl 120 is brought into engagement with a shield 125 secured against movement in the casing 27. Said shield 125 elevates the pawl 120, which is inoperative during the clockvwise movement, out of engagement with the ratchet wheel 122. The crossfeed movement continues, however, under the action of pawl 121,

until the workpiece is reduced to the desired size,

1,971,rss

111, on which the

pawls

120 and 121, and the ratchet wheel 28 are mounted, carries said pawls counterclockwise therewith, but without any corresponding counterclockwise turning of the ratchet wheel 122, the pawl 120 being held in inoperative position by the shield 125, so that the ratchet wheel 122 is not rotated until the pin 124 on the pawl 120 is carried counterclockwise out of engagement with the shield 125, thus allowing the pawl to again engage the ratchet. Continued counterclockwise rotation of the hand wheel procures a corresponding counterclockwise rotation of the ratchet wheel 122 and a resultant retraction of the crossfeed movement.

The change in the relative angular position of the annular member 111 and the ratchet wheel 122 resulting from the above described compensatory mechanism provides for retraction of the

cams

61 and 63 into proper position for a subsequent grinding operation (substantially the position shown in Fig. 3). At the same time, the crossfeed slide is not retracted to its position at the beginning of the preceding grinding movement but rather to a position slightly in advance of its position at the beginning of the preceding grinding operation which distance is substantially equal to the greatest reduction in size of the grinding wheel during any grinding operation, with enough additional advance to assure positive engagement between the grinding wheel and the dressing tool during the subsequent grinding operation. Since the cam 63 is always in predetermined spaced relation to the pawl 120, it will be apparent that when the grinding operation is brought to a close, the pin 124 on the pawl 120 will always be in the same position relative to the shield 125 so that the compensatory mechanism provides for a uniform compensatory nzovement during each succeeding grinding opera ran.

The compensatory movement obviously is dependent upon the position of the shield 125 relative to the pawl or the pin 124 at the end of each grinding operation. The shield is arranged to be adjustably positioned so that the compensatory movement obtained during the retraction of the crossfeed movement will be substantially equal to the greatest reduction in size of the grinding wheel during any grinding operation. Referring now to Fig. 6, the shield 125 is carried by a plate 126 secured against rotation on a shaft 127, the latter having secured on its opposite end a knurled nut 128. The casing 27 is provided with an arcuate slot 130 concentric to the shaft 26, and this slot receives a sleeve 131 having a shoulder which engages the inner surface of the casing. A nut 132 on a threaded portion of the sleeve engages the outer surface of the casing for clamping the sleeve in fixed position in the arcuate slot. The shaft 127 is slidable within the sleeve and a spring 133 urges said shaft toward the left, Fig. 6, to urge the knurled nut against the end of said sleeve, thereby maintaining the shield 125 in a position for engagement with the pin 124 on the pawl. The plate 126 has a projecting stud 134 which engages one edge of the slot 130 to aid in maintaining the shield in proper position, as shown in Fig. 5.

The knurled nut 128, which is positively secured to the shaft 127, has a projecting pin 135 engaging a recess in the sleeve 131 and the shield 125 is withdrawn from operative position by movement of the nut 128 to the right, Fig. 6, thereby drawing the shield to the right therewith. Subsequent turning of the knurled nut 128 causes the pin 135 to engage the end of said sleeve in a position spaced from the recess which normally receives said pin, thus retaining the shield in inoperative position. In this manner, it is possible to avoid the compensatory movement and cause the ratchet wheel 122 to rotate as a unit with the ratchet wheel 28 at all times. The position of the shield 125 is readily adjusted by loosening the clamping nut 132 to permit shifting of the sleeve 131 in the slot 130.

In setting up the machine, it is desirable to provide for rotation of the ratchet wheel 28 and the annular member 111 secured thereto, as well

as'the cams

61 and 63 which are mounted on said member, said rotation occurring without a corresponding rotation of the ratchet wheel 122, or the crossfeed shaft. For this purpose, the annular member 111 has a shaft 136, Fig. 5, journaled therein, to the inner end of which is secured an eccentric disc 137 in a position for engagement with projecting

lugs

138 and 140 on the

pawls

120 and 121 respectively. The forward end of the shaft 136 is provided with a pinion 141 for engagement with a series of gear teeth 142 provided by a ring 143 rotatable on the annular member 111 and held against removal therefrom by the heads of the bolts 110. By a manual turning of the ring 143, the eccentric disc 137 is brought into engagement with the

lugs

138 and 140, thereby raising both of the

pawls

120 and 121 out of engagement with the ratchet wheel 122. The position of the

cams

61 and 63 relative to the pin 62 and adjusting screw 64 respectively, at the beginning of the grinding operation, may thus be varied in accordance with the amount of material to be removed from the workpiece being ground.

To prevent undesired movement of the annular member 111, it is provided with an annular ring 144, Fig. 4, secured against rotation relative to said member by bolts 145 passing through said annular member. The ring is normally urged by springs 146 into engagement with a flange 147 secured against rotation on the shaft 26, said annular ring acting as a brake for the hand wheel and the annular member movable therewith.

The operation of the

pawls

120 and 121 for compensating for the reduction in size of the grinding wheel will be apparent from the foregoing description. It will be noted that, during each retraction of the crossfeed movement between successive grinding operations, the compensatory movement is always uniform regardless of the actual reduction in size of the grind-. ing wheel. The extent of the compensatory movement which is determined by the position of the shield 125 may be varied as desired; but it is necessary for proper operation that the compensatory movementin each case be at least as great as the greatest reduction in size of the grinding wheel during any grinding operation with enough additional compensatory movement for obtaining positive contact between the grinding wheel and the dressing tool during the subsequent dressing operation.

The retraction of the crossfeed movement is procured in any suitable manner either by manual counterclockwise rotation of the hand wheel 113 .or may be procured by any suitable automatic piece. By the uniform retraction, the cutting surface of the grinding wheel is positioned in predetermined relation to the axis of rotation of the workpiece regardless of the reduction in size of the Wheel. The uniform counterclockwise movement of the hand wheel, if manually procured, is determined by a ring 148, Fig. 4, which is positioned on the sleeve 112 for rotation as a unit with said hand wheel, said ring carrying indicia cooperating with an indicating protuberance 150 on the casing 2'7. By the uniform counterclockwise turning movement of the hand wheel, a retraction of the crossfeed movement is pro cured which repositions the grinding wheel in readiness for a subsequent grinding operation with the cutting surface of the grinding wheel in predetermined relation to the axis of the workpiece, since the compensatory mechanism provides for a retraction of the crossfeed movement which is slightly less than the actual crossfeed movement, thereby compensating for the reduction in size of the grinding wheel. The uniform retraction of the hand wheel procures a corresponding uniform retraction of the annular member 111 carrying the

cams

61 and 63 so that the latter are always returned to the same original position in readiness for each successive grinding operation. It will be noted that the ratchet wheel 28, the

cams

61 and 63, the member 111,

the

pawls

120 and 121, and the hand wheel 113 all turn either clockwise or counterclockwise as a unit, and the compensatory movement takes place between said unit and the ratchet wheel 122 which is directly connected to the crossfeed screw for actuating the same.

Although the above described crossfeed mechanism with its associated compensatory mechanism has been described in connection with instrumentalities of the type disclosed in the Guild Patent No. 1,682,672, the mechanism is also operable in connection with grinding machines of the type disclosed in the above-cited Guild and Burns Patent No. 1,830,358 in which the separation of the grinding Wheel from the workpiece for the dressing operation is under the control of a cam on the crossfeed mechanism corresponding to the cam 63 above described, and the final size of the workpiece is determined by a suitable gage mechanism such as that shown in the Congadson, et al. Patent No. 1,534,302, above cite The wiring diagram for the machine, when the above described crossfeed mechanism is used in connection with the instrumentalities of the Guild and Burns patent above cited, is shown in 180 Fig. 9. Referring to this figure, the cam 63', corresponding to the cam 63 above described, engages, during the grinding operation, an adjustable screw 64 for rocking the lever 65' in which said screw is mounted, thereby procuring 185 engagement between contacts 66 and 68'. When the

contacts

66 and 68 are brought together, a circuit is closed as in the case of the

contacts

66 and 68 above described, thereby procuring a dressing operation on the grinding wheel. To this end, the contact 68' is connected by a lead 77' to one terminal of an electromagnet 78 and the other terminal of said magnet is connected by a lead 80' to one terminal 81' of a switch 82' corresponding to the switch 82 above. The other ter-- minal 83' of the switch is connected by a lead 84' to a suitable source of power 85'. Energization of the electromagnet 78' by engagement of the contacts 66' and 68 causes attraction of an armature 88' to procure in the manner above de- 5 piece.

scribed, with reference to the armature 88, an extended movement of the table to the left and swinging movement of the dressing tool into operative position for a dressing operation on the grinding wheel.

After the dressing operation, the workpiece and the grinding wheel are then returned to operative position and the grinding operation continues until spaced

contacts

151 and 152 are brought together. These contacts correspond to the well-known gage contacts which may be of the type disclosed in the Conradson, et al. Patent No. 1,534,302 above cited, or in the above identified Guild and Burns Patent No. 1,830,358; it is sufiicient to note that, when the workpiece reaches the desired size, a gage enters the bore of the workpiece and allows the contacts to be brought together. The contact 151 is grounded at 153 and the contact 152 is connected by a lead 154 to one terminal of an electromagnet 105', the other terminal of which is connected by a lead 106' to the generator 85'. Engagement between the

contacts

151 and 152 closes a circuit which energizes the magnet 105' causing attraction of the armature 107', thereby procuring a. second extended movement of the carriage to the left by the mechanism above described in connection with the armature 107 and the electromagnet 105. This extended movement of the carriage to the left brings the grinding operation to a close.

During this grinding operation, the crossfeed mechanism has been advanced so that the pin 124 on the pawl 120 has engaged and been elevated by the shield 125, thereby withdrawing the pawl 120 from engagement with the ratchet wheel 122. The pawl 120 is in predetermined relation to the shield 125 when the dressing operation is procured through the actuation of the adjustable screw 64 by the cam 63', Fig. 9. The subsequent crossfeed movement after the dressing operation is variable, however, as determined by the necessary crossfeed movement before the gage member, which controls the position of the

gage contacts

151 and 152, may enter the work- The relative position of the pin 124 on the shield 125 at the end of each grinding operation, when the machine is under the control of a gage mechanism is thus variable, and a subsequent retraction of the crossfeed movement results in a variable compensatory movement which is proportional to the actual reduction in size of the grinding wheel. Said compensatory movement must obviously be slightly greater than the actual reduction in size of the grinding wheel to provide for positive contact between the grinding wheel and the dressing tool during a subsequent grinding operation.

It will thus be noted that the crossfeed mechanism, which operates satisfactorily for controlling the final size of the workpiece by mechanism of the ,type disclosed in the above-cited Guild Patent No. 1,682,672 in which case a uniform compensatory movement must be provided, is also operable in connection with mechanisms of the type disclosed in the Guild and Burns patent in which the final size of the workpiece is under the control of a gage in which case a variable compensatory movement must be provided. In the latter case, the compensatory movement operates to vary the position of the cam 63' relative to the crossfeed screw or to the actuating ratchet 122 so that the dressing operation will be procured at substantially the same time during each successive grinding operation before the workpiece reaches the desired finished size.

The crossfeed mechanism and the compensatory mechanism associated therewith is thus applicable not only to machines involving a fixed amount of compensatory movement, such as that in the Guild Patent No. 1,682,672 above cited, but also in machines of the type in the Guild and Burns Patent No. 1,830,358, which involve a variable compensatory movement for which, prior to the present invention, it has been necessary to provide a slip ring arrangement. Furthermore, by moving the shield 125 to inoperative position, it is possible to avoid any compensatory movement whatever, so that the crossfeed movement or the retraction thereof will be obtained directly from a turning movement of the hand wheel without a change in the relative positions or the actuating ratchet 28 and the ratchet 122.

I claim,

1. In a crossfeed mechanism, a slide, a crossfeed screw connected to said slide, a positively actuated member for procuring turning movement of said screw for actuation of the slide, means to procure a positive turning movement of said screw with said member during and in response to actuation of said member in one direction, and means to provide for a relative angular shifting movement between said member and said screw during a portion of the actuation of said member in the other direction, said last means providing for a positive actuation of said screw by said member during the remainder of the actuation of said member in said other direction.

2. In a crossfeed mechanism, a slide, a crossfeed screw connected to said slide, a positively actuated member for procuring turning movement of said screw for actuation of the slide, means including a pawl to provide a connection between said member and screw for procuring a positive turning movement of said screw in response to actuation of said member in one direction, and means including a pawl to provide for a relative angular shifting movement between said member and screw during the actuation of said member in the other direction, said last-mentioned pawl being inoperative during a portion of the movement of said member.

3. In a crossfeed mechanism, a. slide, a crossfeed screw connected to said slide, a positively actuated member for procuring turning movement of said screw for actuation of the slide. means to procure a positive turning movement of said screw with said member during and in response to actuation of said member in one direction, and means including a pawl and ratchet to provide for a relative angular shifting movement between said member and screw during the actuation of said member. in the other direction, said pawl being maintained out of engagement with the ratchet wheel during a portion of the movement of said member.

4. In a crossfeed mechanism, a slide, a crossfeed screw connected to said slide, a positively actuated member for procuring turning move-' ment of said screw for actuation of the slide, a ratchet wheel connected to the crossfeed screw, pawls on said positively actuated member and engaging said ratchet wheel for procuring positive turning movement of said ratchet wheel in response to movement of said member in either direction, and means to withdraw one of said pawls from operative engagement with the ratchet wheel to provide for a relative angular shifting movement between said member and ratchet wheel during the actuation of said member in one direction. v

5. In a crossfeed mechanisms slide, a crossieed screw connected to said slide, a positively actuated member for procuring turning movement of said screw for actuation of the slide, a ratchet wheel connected to the crossteed screw, pawls on said positively actuated member and engaging said ratchet wheel for procuring positive turning movement of said ratchet wheel in response to movement of said member in either direction, and a shield positioned for withdrawing one of said pawls from engagement with the ratchet wheel during a portion of the movement of said member, thereby providing tor a relative angular shitting movement between said positively actuated'member and said screw.

6. In a crossfeed mechanism, a slide. a crossfeed screw connected to said slide a positively actuated member for procuring turning movement of said screw for actuation of the slide, a ratchet wheel connected to the crossieed screw, pawls on said positively actuated member and engaging said ratchet wheel for procuring positive turning movement of said ratchet'wheel in response to movement of said member in either direction, and a shield normally positioned for retraction of one of said pawls from engagement with the ratchet wheel-during a portion of the movement of said member, thereby providing for a relative-angular shifting movement between said member and the ratchet wheel, said shield being adjustable to vary the extent of the angular shifting movement.

7a In a crossfeed mechanism, a slide, a crossfeed screw connected to said slide, a positively actuated member for procuring turning movement of said screw for actuation of the slide, a ratchet wheel connected to the crossfeed screw, pawls on said positively actuated member and engaging said ratchet wheel for procuring positive turning movement of said ratchet wheel in response to movement of said member in either direction, a shield positioned for withdrawing one of said pawls from engagement with the ratchet wheel during 'a portion of the movement of said member, thereby providing for a relative angular shifting movement between said positively actuated member and said screw, and means to render said shield inoperative to procure rotation of said ratchet wheel as a unit with said member in either direction of movement of said member.

8. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossfeed movement between said grinding member and a workpiece in said work-supporting member, said mechanism comprising a positively actuated member, a crossfeed screw, means under the control of said member for procuring a change in the grinding operation, and connections between said screw and member to procure a positive turning movement of said screw in response to actuation of said member in one direction, thereby procuring a definite crossfeed movement and to procure a relative angular shifting movement between said screw and member in the other direction of movement of said member for compensating for the reduction in size of the grinding member.

9. In a grinding machine for the successive reduction or a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossfeed movement between said grinding member and a workpiece in said reduction in size of the grinding member.

work-supporting member, said crossfeed mechanism comprising an angularly movable member, means to actuate said member to procure the crossieed movement, control means on said member tor procuring a change in the grinding operation, a crossieed screw, means providing a connection between said screw and member to procure a positive turning. movement of said screw in response to turning movement of said member in one direction, and means including a pawl and ratchet to provide for a relative angular shitting movement between said screw and member during the movement of said member in the opposite direction, thereby compensating for the 10. Ina grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossieed mechanism for procuring a relative crossfeed movement between said grinding member and a workpiece in said work-supporting member, said crossieed mechanism comprising an angularly movable member, means positioned on said member for procuring a change in the grinding operation, a crossfeed screw, a ratchet wheel connected to said screw, and pawls carried by said member and engaging said ratchet wheel to procure positive turning movement of said ratchet wheel in response to movement of said member, and means to render one of said pawls inoperative during a portion of the movement of said member to procure a relative angular shifting movement between said ratchet wheel and the member to compensate 'for the reduction in size of the grinding member.

11. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossfeed movement between said grinding member and a workpiece in said work-supporting member, said crossfeed mechanism comprising an angularly movable member, means on said member for. procuring a change in the grinding operation, a crossfeed screw, a ratchet wheel connected to said screw, pawls on said member for procuring a positive ,turning movement of said ratchet in response to'turning movement of said member, anda shield for rendering one 01 said pawls inoperative during a i255 portion of the movement of sai member to procure a relative angular shifting movement between said screw and member during the movement of said member in one direction, thereby compensating for the reduction in size oi. the 13d grinding member.

12. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, agrinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossieed movement between said grinding member and aworkpiece in said work-supporting member, said crossfeed mechanism comprising an angularly movable member,

means on said'member for procuring cessation of the grinding operation when a workpiece in said work-supporting member reaches the desired size, a crossfeed screw and connections between said screw and member to procure a positive turning movement of said screw in response to actuation of said member in one direction, thereby procuring a positive crossieed movement between the grinding member and the workpiece,

said connections providing for a relative angular shifting movement between said screw and member in the other direction of movement of said member, thereby compensating, during the retraction of the crossfeed movement, for the reduction in size of the grinding member.

13. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossfeed movement between said girnding member and a workpiece in said worksupporting member, said crossieed mechanism comprising an angularly movable member, means under the control of said member for procuring cessation of the grinding operation when the workpiece reaches the desired size, a crossieed screw, means to procure a positive turning movement of said screw in unison with said member during the movement of said member in one direction'for procuring a definite crossfeed movement between said grinding member and a workpiece, and means including a pawl for providing for a relative angular shifting movement between said member and screw during the movement of said member in the opposite direction, said pawl being inoperative during a portion of the movement of said member in said opposite direction, said angular shifting movement compensating for the reduction in size of the grinding operation.

14. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossfeed movement between said grinding member and a workpiece in said work-supporting member, said crossfeed movement comprising an angularly movable member having a predetermined movement in one direction for procuring the crossfeed movement and a corresponding movement in the opposite direction for a retraction of the crossfeed. movement, means under the control of said member for procuring a change in the grinding operation, a crossfeed screw and connections between said screw and member to procure a positive turning movement of said screw in response to actuation of said member in one direction for a predetermined advance between the grinding member and the workpiece, said connections also providing for a relative angular shifting movement etween said screw and member during the movement of said member in the opposite direction, the latter movement procuring a separation of the grinding member from the workpiece, said retraction being less in extent than the advancing movement, thereby compensating for the reduction in size of the grinding member, said angular shifting movement being uniform during each successive retraction of the crossfeed movement.

15. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossfeed movement between said grinding member and a workpiece in said work-supporting member, said;- crossfeed mechanism comprising an angularly movable member, means positioned on said member for procuring a change in the grinding operation, a crossfeed screw,'a ratchet wheel connected to said screw, and pawls carried by said member and engaging said ratchet wheel to procure positive turning movement of said ratchet wheel in response to movement of said member, means to render one of said pawls inoperative during a portion of the movement of said member to procure a relative angular shifting movement between said ratchet wheel and the member to compensate for the reduction in size of the grinding member, and

.member, by movement in one direction, advancing the slide, and by movement in the opposite direction, retracting said slide, and connections between said means and said member for procuring a positive actuation of said means throughout the entire movement of said member in one direction, and procuring a positive actuation of said means througha portion only of the movement of said member in'the opposite direction.

17. In a crossfeed mechanism, a slide, means engaging said slide for movement thereof in response to actuation of said means, a positively actuated member for actuating said means, means including a pawl to provide a connectionbetween said member and; said means for procuring a positive actuation of said means in response to actuation of said member in one direction, and means including a pawl to provide for a relative shifting movement between said member and means during the actuation of said member in the other direction, said last-mentioned pawl being inoperative during a portion of the movement of said member.

18. In a crossfeed mechanism, a slide, means engaging said slide for movement thereof in response to actuation of said means, a positively actuated member for actuating-said means and thereby said slide, means for procuring a positive actuation of said means during and in response to actuation of said member in one direction, and means including a pawl and ratchet to provide for a relative shifting movement between said member and said means during the actuation 01 said member in the other direction, said pawl being maintained out of engagement with the ratchet wheel during a portion of the movement of said member.

19. In a crossfeed mechanism, means including a ratchet wheel connected to said slide for movement thereof, a positively actuated member for procuring turning, movement of said ratchet wheel for actuation of the slide, pawls on said positively actuated member and engaging said ratchet wheel in response to movement oi. said member in either direction, and means to withdraw one of said pawls from operative engagement with the ratchet wheel to provide for a relative angular shifting movement between said member and ratchet wheel during the actuation of said member in one direction.

20. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative erossfeed movement between said grinding member and a workpiece in said work-supporting member, said mechanism comprising means including a ratchet wheel whose actuation provides the crossfeed movement, a positively actuated member, means under the control of said member for procuring a change in the grinding operation, and connections between said ratchet wheel and member for procuring a positive turning movement of said wheel in response to actuation of said member in one direction, and for procuring a relative angular shifting movement between said wheel and member in the other direction 01' movement of said member, thereby compensating for the reduction in size of the grinding member.

21. In a grinding machine for the successive reduction of a plurality of workpieces all to the same size, a grinding member and a work-supporting member, a crossfeed mechanism for procuring a relative crossteed movement between said grinding member and a workpiece in said work-supporting member, said mechanism comprising a positively actuated member, a crossteed shaft, means under the control or said member for procuring a change in the grinding operation, and connections between said shaft and member to procure a positive turning movement of said shaft in response to actuation of said member in one direction, thereby procuring a definite crossfeed movement and to procure a relative angular shifting movement between said shaft and member in the other direction of movement of said member for compensating for the reduction in size of the grinding member.

WALDO J. GUILD.