US1961849A - Grinding machine - Google Patents

Description

W. F. FRASER GRINDING MACHINE -Jue 5, 1934.

4 sheets-sheet' 2 Filed sept. 7, 1928y MII/l ln/vento@ WARREN E Frinqsafiamm,

w. Yr'. FRASER GRINDING' MACHINE Julie 5', 1934.

Filed sept. 7, 1928'. sheetsvsneet 'sm M n @mi W m M M ...m oo rl.

W. F. FRASER GRINDING MACHINE June 5, 1934.

Filed Sept. '7, 1928 4 Sheets-Sheet` 4 In/manto@ UNITED STATES PATENT OFFICE GRINDING MACHINE Warren F. Fraser, Westboro, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application September 7, 1928, Serial No. 304,468

`29 Claims. (Cl. 51-95) This invention relates to grinding machines of ment and providing means for moving the grindthat type in which the work piece and the grinding element rapidly until arrested by said stop ing element are moved automatically toward and and for thereafter maintaining a continuing presfrom each other for effecting' the grinding opsure while the stop is slowly retracteda At the eration and then for effecting the separation of conclusion of the retracting movement of the 60 the ground work piece and the grinding elestop, the direction of pressure upon the grindmem-, ing element is reversed and the latter is returned In one of its aspects, the present invention to its initial position at its original relatively consists in improved mechanism for effecting an high rate of speed.

extremely accurate and positively controlled ap- While the desired results could be secured by 65 preaching movement of the grinding element and mechanical means, I prefer to employ, in part, a the work, such movement constituting the grindfluid pressure system and this possesses imporing feed. This operation should be carried out tant advantages in its facility of control as to with the most precise accuracy both as to rate Speed 0f Operation and uniformity 0f action.

and extent of movement, and also the point of Other features of the invention consist in 70 limitation or end of such movement must be connovel mechanism for controlling the rate of trolled with extreme accuracy, in order to insure movement of the grinding element and for de that successive pieces of work shall be ground terminil'ig pOStiVely and adjustably its DOD 0f to exactly the same size. With these conditions termination and also the location of its path with in View, an important feature' of the invention respect to the Work piece. Still another fea- 75 consists in means for exerting upon the grinding ture of the invention relates to the construction element a continuous and uniform pressure tend- 0f the WOIk SUIJDOI and COIiSiStS in a novel ar- `ing to move it toward the work piece, in comrangement of ways for insuring accurate travel bination with a stop positively located and arthereof and uniform behavoir when moved to ranged to be positively and accurately retracted DIGSED" a Series 0f longitudinally spaced ob- 80 so that the grinding element may follow it up in J'eCtS O1' blanks in the Work piece in grinding the same manner. As herein shown and in ac- DOSiGiOncordance with a preferred embodiment of the These and other features of the invention will invention, the stop has a threaded portion cobe best understood and appleeiated from the fol- 0 operating with a nut which is rotated at a def- 10Wir1g description 0f a Preferred embodiment 85 inite rate and through a predetermined angle to thereof, selected for purposes of illustration and shift the stop in the desired manner. shown in the accompanying drawings, inwhich In addition to the approaching movement for Fig. 1 isa view in front elevation of the entire the grinding feed above discussed, which takes machine;

place at a relatively slow rate, it is desirable to Fig. 2 iS a View in end elevation of the ma- 90 make provision for a separating and approachchine as Seen from the right, a portion of the base ing movement at a higher rate of speed during being broken away; the non-grinding time of the machine. This is Fig. 3 is a sectional View on line 3-3 of Fig.v for the purpose of aording clearance for re- 1 and on an enlarged scale;

40 moving or replacing the workin the machine or Fig. 4 is a detail sectional view on line 4 4 95 for gauging the same or for clearing portions of Fig. 3; ofthe work when moving it from one grinding Fig. 5 is a detail sectional view on line 5 5 of position to another as, for example, in grinding Fig. 3; crank shafts. In another aspect, therefore, the Fig. 6 is .a view in horizontal section of the 4.5 present invention comprises improved mechanism control valve on line 6-6 of Fig. 1; 100

for imparting to the grinding element a pre- Fig. '7 is a View in vertical section of the reguliminary approaching movement at a relatively lating valves on line 7-7 of Fig. 2; and high speed, to be followed by a further movement Fig. 8 is a diagrammatic View of the fluid presin the same direction at a lower rate constitutsure system.

ing the grinding feed, and this, in turn, to be The base of the machine comprises a casing 105 followed by a separating movement, returning the 10, generally rectangular in shape and provided parts to initial position again at a high rate of with longitudinal ways in its upper forward porspeed. In this connection, an important feaf tion for the work support, which comprises a ture of the invention consists in locating a stop table 13. At its front edge, the table 13 has a .in the path of movement of the grinding eledownwardly projecting portion of V-shaped cross section which fits in the ways 12, shaped to correspond thereto. At its rear edge, the table 13 has a plane longitudinally extending surface which rests upon the flat ways 11; verse position of the table is, therefore, definitely and accurately controlled by the cooperating V-shaped elements while the plane surfaces at the rear edge of the table are universally accommodating. Longitudinal movement of the table may be eiected by any well-knownmeans such, for example, as a rack 14 secured tothe lower face of the table between the ways 11 and 12 and a pinion 15. The pinion 15 is mounted on the rear end of an intermediate shaft 17, which carries a gear wheel 16 at its forward end ,meshing with a pinion 18 on a shaft 19 journaled in a bracket 21 attached to the base 10 and carrying at its outer end a hand wheel 20.

The table 13 carries a tailstock 28 and a headstock 29 of usual commercial construction, adapted to support the work piece between them. 'I'he headstock 29 includes a driving pulley 30 and this may be connected by a belt 31 to any convenient source of power.

The grinding element comprises a wheel 35 mounted on a spindle 36, which is rotatably mounted in bearings 37 and 38 formed in the upper portion of a carrier comprising a slide 39. The slide 39 is mounted for movement toward and from the work support in ways 40 and 41 formed upon the upper surface of the base 10. The spindle 36 carries a driven pulley 42 which is located between the bearings 37 and 38 and which may be driven by a belt 43 from any convenient source of power.

'Ihe machine thus far described, except for the shape of the table 13 and its ways which have been specifically mentioned, is of well-known commercial construction and, therefore, requires no further detail description.

As herein shown, the approaching and separating movements of the grinding element and the work piece are effected by moving the grinding element, although in many aspects it is of secondary importance which of the two is actu- .ally moved. The movements of the grinding wheel may be divided into two steps: first, a rapid movement toward and away from the work, taking place during the non-grinding operation of the machine cycle, and, second, a slow movement of the grinding wheel during the grinding portion of the cycle. 'I'he rst step referred to is secured by the employment of a lluid pressure mechanism interposed between the grinding wheel carrier slide and the base of the machine, and the second step is derived from'the same mechanism but varied and controlled in its rate of movement by a positively acting stop positioned and moved as will be described.

The lower portion of the slide 39 is provided with a series of longitudinally aligned bores 44-45-46. vWithin the bores 44 and 45 is disposed an hydraulic cylinder 47 which is secured against rotation by an internal key 48, set in the base of the slide 39 and projecting into a keyway 49 formed in the outer surface of the cylinder 47. The rear end of the cylinder is closed by a head 50 having a rearwardly ex,- tending portion' 51 threaded to receive a nut 52, which is rotatably mounted in a bearing 53 secured in the rearmost bore 46 in the slide 39. The nut 52 is secured against endwise movement in the bearing 53 by means of a shoulder 60 formed at the rear end of the nut and thrust bearings 61 and 62 which are held in assembled The transjustment to be made conveniently bythe oper'- ator, a worm wheel 64 is secured to the shoulder 60 of the nut and arranged to mesh with a worm, not shown, secured to a shaft 65, the lower end of which is journaled in an extended portion 66 of the flange 53. 'Ihe shaft 65 extends upwardly to a housing 67 carried by a bracket 68 attached to the slide 39, where it is connected by suitable gearing to a shaft 69 extending through a bearing 70 to the front of the machine, where it is provided with a hand wheel 71. By means of the mechanism thus far described, the operator, from his normal position'in front of the machine, can readily rotate the hand wheel 71 and thereby adjust the cylinder 47 forwardly or rearwardly with respect to the slide 39.

'I'he front end of the cylinder 47 is provided with a' head 80 having a forwardly extending portion 81 adapted to engage a stop 82 which acts to limit and control the forward movement of the cylinder 47 and the slide 39 which carries it. In the initial or rearmost position of the slide 39, the portion 81 is separated from the stop 82 by a distance corresponding in extent to the clearance or high speed travel of the carrier. In Fig. 3, the carrier slide is shown in its extreme forward position at the conclusion of its grinding feed movement, in which the portion 81 of the cylinder hasnot only been moved into contact with the stop 82 but has followed the retracting movement of the stop to the limiting position of the latter.

The cylinder 47 has an elongated opening 83 in the lower central portion thereof and is'provided with a stationary piston 84 so proportioned that at neither extreme position of the cylinder will the opening 83 be uncovered by the piston. The pisto 84 is provided with a transverse opening into which projects the end of a vertically disposed post 86, the latter being slidably but closely fitted therein. The lower end of the post 86 is pivotally secured within the base 10 by means of screws 87 and 88, having threaded connection with lugs or ears 89 and 90 on the base. The postl 86 extends upwardly through an opening 95 in the casing of the base, which opening fit-s the post closely in" a direction from front to rear or axially of the cylinder 47 but with some clearance in a lateral direction, as shown in Fig. 4. 'Ihe post, therefore, positively prevents longitudinal movement of the piston 84 vrelatively to the base 10 and at the same time permits a lateral movement of accommodation to the piston, thereby permitting the carrier slide 39 containing the cylinder 47 to assume such position on the ways 40 and 41 as is determined by gravity alone.

The post 86 is provided with a longitudinally extendingpassage 96 having an opening 97 at its lower end and connecting at its upper end with a passage 98 extending through the forward portion of the piston 84 and opening into the front end of the cylinder 47. The post 86 is also provided with a parallel passage 100 leading from an opening 101 at its lower end to the passage 102 in the rear portion lof the piston and leading to the rear end of the cylinder. By controlling the flow of fluid under pressure through the openings 97 and 101 and to the front or rear /lends of the cylinder 47, the cylinder with its Y from the work support. The limit of this movement is determined by the relative lengths of the piston 84 and the cylinder 47 but inasmuch as the position of the cylinder with reference to the carrier slide 39 may be adjusted by turning the nut 52 from the hand wheel 71, the location I of the path of travel of the grinding wheel may be varied and regulated, as will be apparent. For example, if the nut.52 is turned so as to shift the cylinder forwardly with respect to the carrier slide` 39, thel path of the latter will then terminate at a point further from the axis of the work piece than if the cylinder 47 is adjusted forwardly with respect to the carrier slide 39. y l

The required' precise control of the slow or grinding feed movement of the carrier slide 39 is obtained by retractingv the stop 82 while the carrier slide is held in contact with it by fluid pressure admitted to the forward end of the cylinder. 'I'he stopl 82 is slidably mounted in a bracket 110 secured to the casing of the base and is held against rotation by a pin 111 projecting fromY the bracket 110 and slidably engaging a slot 112 in a flange 113 secured to the front end of the stop. The intermediate portion of' the stop is provided with a screw thread 114 of right-hand lead for engagement with a sleeve 115, A thrust bearing 116 is interposed between the sleeve and the front bearing 117 for the stop. A gear 118 is rigidly secured to the sleeve v115 and may be rotated by means of a rack 119 which meshes with its lower side and is formed upon an `extended .portion of a piston rod 120. The piston rod, as shown in Figs. 1 and 8, extends from apiston 122 in a fluid pressure cylinder 121 attached to the base casing 10. The piston rod 120 passes through a stationary bracket 123 attached to the casing 10 and carries a pair of threaded adjustable collars or stops 124 and 125. These, by making contact witheither side of the bracket 123, serve to limit the motion of the rack 119 and the gear 118 in either direction, thereby controlling precisely the extent and limit of the longitudinal movement of the stop 82 and, consequently, determining the forward limit of movement of the carriage slide 39 and v associated parts.

Means to control the rate of movement of the rack 119 in the direction required for producing a recedingmovement'of the stop 82 toward the front of machine and thereby the grinding feed of wheel toward the Work will now be described. A fluid reservoir comprising a tank 130 is located at any convenient point within the casing 10.

A feed pipe 131 connects this tank with a pump 132 of any well-known construction which may be attached to the base 10 andl driven by a pulley 133 and a belt 134 from any convenient source of power to maintain a continuous uniform fluid pressure inthe entire system.

A pipe line 135 connects the outlet of the pump 132 with a valve body 136 secured to the'base 10.

The valve body 136 is'providedl with ports or passages 137-138-139-140 and 141, the portv 137 connecting with the discharge or pressure pipe 135.A The valve body is also provided with a piston valve 142 adapted to connect inlet port 137 with outlet port 138 and port 139 to port 140 when in the position shown in Fig; 6, and when in its other extreme position to connect inlet port 137 to port 139 and port 138 to port 141. 'I'he 155 and 157.and valve vthrough the pipe 159,

valve 142 has a stem 143 extending through the lhead 144 of .the valve b ody 136 andthis is engaged by the lower.end,145 of a vhand lever 146 which is pivotally mounted-at147 in a bracket 148 secured to the valve body 136.

A pipe line 155 is connected'with port 138 and branches at a T 156, see Fig. 8. One branch 157 leads through. a regulating valve 158 and pipe 159 to the right-hand end of the cylinder 121. The other branch 160 leadscto the opening 97 in the post 86 and is connected through passages 96and 98 with-the forward end of the cylinder A pipe line 161 connects with port 139 and branches ata T 162. One branch 163 connects with the left-handend of the cylinder 121 and another branch 164 connects with the opening 101 in the post 86 and passage 100 leading-to rear end of the cylinder 47. Ports 140 and,141. are connected by a passage 165 in the valve body 136, see Fig. 6, and a pipe line 166 connects said passage 165 with the tank 130.

A regulating valve, designated as a whole by the reference character 158 and shown in Fig. 7, consists of a body 175 having a chamber 176 therein and a lower cap 177 having a chamber 178. The chambers 176 and 178 are connected by a port 179 and the size of the connecting port may be varied or adjusted by means of a valveV 'I'he chambers 176 and 178 are also connected by a second port 183 but this connecting port is closed against the flow of fluid from the lower chamber 178 to the upper chamber 176 -by a valve 184 normally held to its seat by a spring 185. Said valve and spring do not offer any substantial resistance to the reverse flow of -fiuid from the chamber 176 to the chamber 178. A screw cap 186 seals the outer'end of valve stem guide 187. Y

The manner in which the machine operates will be apparent from the foregoingdescrption but willv be outlined as follows: the workpiece to beground between the head and tailstocks 28 and 29 and starts :rotation of the same. He then moves of thehand wheel 20 until the work is properly positioned in front of the grinding wheel 35. He then swings the lever 146 to the front and this -actionmoves the valve 142 to the position shown in Fig. 6.v Fluid under pressure now 'flows from thepipe 135 through 158, its rate of ow being controlled by the setting of the valve 180, thence the right-hand` end of the cylinder 121 and slowly moving-the piston 122 to the left, causing a slow recessional movement of the stop 82. y

At the same time, uid flows through the other branch 160 of the pipe 155 to the forward end of the. cylinder 47, quickly moving the cylinder 47 and the slide 39 to the front until their movementis arrested by contact with the stop- 82. Thereafter, the fluid pressure will cause these 'parts to move toward the front only as permitted the collar 125 on the piston rod 120 makes contactrwlth the bracket 123. After allowing the The.. operator places the table 1 3 by meansports 137 and 138, pipes n a base member, of a slide member, work supportwheel and work to remain in contact for Whatever time is desired to enable the wheel to grind itself out in work or to remove the effects of spring, or give, in the machine, the operator swings the lever 146 toward .the rear of the machine. The valve 142 is thereby shifted to connect the port 137 with port 139 and the port 138 with port 141 and fluid now flows from the pipe 135 through pipe 161 and its branches 163 and 164 to theleft-hand end of the cylinder 121 and rear end of the cylinder 47. Fluid flows from the forward end of the cylinder 47 through the pipe 160 and from the right-hand end of the cylinder 121 through pipe 159 and passages 176, 179, 183 and 178 of valve 158 and pipe 157 to the pipe 155, to port 138 and port 141 through passage 165 and the pipe 166 back to the tank 130. By this action, the carrier slide 39 with the grinding wheel will be returned rapidly to its initial position, so that the operator may remove the work and insert another piece'. Meanwhile, the stop 82 moves at a slower rate back to its initial position and the machine is in readiness for grinding a new work piece or a new blank on the same piece.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding machine comprising a base, a grinding wheel, a movable support therefor, a work support, fluid pressure operated wheel feeding mechanism arranged to continuously move the wheel support toward and from the work, and a fluid pressure operated device including a movable stop member cooperating with the wheel feed mechanism and a valve controlling means for regulating the rate of movement of said stop, whereby the rate of feed of the grinding wheel toward the work may be automatically controlled and stopped at any predetermined position.

2. In a grinding machine, the combination with a base, of a slide mounted thereon, a rotatable grinding element mounted upon said slide, a fluid pressure cylinder adjustably mounted in said slide to position the grinding wheel and compensate for wheel wear, a piston in said cylinder having fluid pressure passages leading to opposite sides of the cylinder, connections between said piston and base effective to prevent longitudinal movement of said piston relative to said base, and means to allow transverse move-4 ment of the piston whereby it may easilyadjust itself within the cylinder and aid in preventing leakage of fluid between the cylinder and piston.

3. In a grinding machine, the combination of a base, a carrier mounted thereon, a rotatable grinding element mounted upon said carrier, a fluid pressure cylinder mounted in said carrier, adjustable connections between said cylinder and carrier, a piston in said cylinder having fluid pressure passages opening into opposite ends of the cylinder, connections between said piston and base effective to prevent longitudinal movement of said piston relative to said base, a movable stop member for controlling the movement of said cylinder relative to said base, and means to positively and continuously move the stop member.

4. In a grinding machine, the combination with ing means mounted upon one of said members, a rotatable grinding element mounted upon the other one of said members, a fluid pressure mechanism having two relatively movable parts, operative connections between one of said parts and said base, operative connections between the other one of said parts and said slide, a positive stop for said slide, means to cause said stop to recede at a predetermined rate, and a single manually operable member adapted to set in motion both said fluid pressure mechanism and said means for causing the stop to recede.

5. In a grinding machine, the combination with a base, of a work support and a carrier for a grinding wheel mounted thereon, fluid pressure mechanism for moving said carrier including a cylinder adjustably secured to the carrier and a stationary piston, means for admitting fluid under pressure through the piston to either end of the cylinder, and means for preliminarily adjusting the cylinder with respect to the carrier to vary the limits of the travel of the carrier.

6. In a grinding machine having a frame, a movable slide mounted in the frame, a fluid pressure cylinder having a threaded projection at one end for connection with the slide and a contact piece at the other, and an abutment member mounted in the frame in line with said contact piece, said member being mounted for movement in a positively controlled manner and governing the movement of the slide by its engagement with the contact piece of the cylinder.

'7. In a grinding machine having a frame, a movable grinding wheel slide mounted in the frame, a fluid pressure cylinder connected to the slide and movable therewith, connections concentric with the axis of the cylinder for adjusting the relative position of the cylinder and slide, a stop mounted in the frame at an initial distance from the cylinder determined by its connection to the slide, and means for continuously retracting the stop while it is engaged by the cylinder to control the wheel movement.

8. A grinding machine comprising a base, a Wheel slide mounted thereon, a rotatable grinding wheel on said slide, a fluid pressure cylinder adjust-ably mounted on said slide, a piston within said cylinder having fluid passages leading to opposite ends of the cylinder, connections between the piston and base which prevent longitudinal movement of `the piston relative to the base, a retractable stop member on the base movable to limit and control the movement of the wheel slide and means to continuously retract said stop at a measured rate during the infeed of the grinding wheel towards the work, whereby said feed may be positively controlled irrespective of any pressure changes in the fluid system.

9. A grinding machine comprising a base, a work support thereon, a grinding wheel slide therefor which is movable towards and from the work, fluid pressure mechanism including a fluid pressure operated motor having two relatively movable parts, operative connections between one of said parts and the base, manually adjustable connections between the other one of said parts and the wheel slide, a retractable stop mounted on the base which serves to limit the forward motion of the grinding wheel towards the work,

means for retracting the stop at a controlled rate and permitting movement of the slide and separate precision mechanism for adjusting said connections at any time in order to accurately position the grinding wheel relative to the work without changing the position of said stop and thereby compensating for wheel wear.

10. A grinding machine comprising a base, a grinding wheel slide mounted thereon, a fluid pressure motor the movable member of which is at a measured rate and thereby controlling the rate of slide movement, and adjustable lmeans to vary said rate of continuous movement of the stop, whereby" the grinding wheel may be continuously fed towards the work at a selected and constant rate. A

11. A grinding machine comprising a work support,- a carrier movable towards and `from the work support, a grinding wheel rotatably mounted upon the carrier, power operated mechanism for exerting a continuousyielding pressure on the carrier tending to move the grinding wheel towards the work atan uncontrolled rapid rate, a stop mechanism including a retractable stop arranged to limit and control the rate of wheel feed movement towards the workand a member engageable with the stop, one of said parts being movable with the carrier and the other being mounted onthe base, and power operated'means to positively and continuously retract the stop at a measuredl ratefor a given distance `and thereby control the rate and extent ofgrinding wheel feed into the work.

1,2. A grinding `:machine comprising a base, a

grindingwheel, a support therefor movable to feed the Wheel towards the work, means-applying a yieldable force tending to move said support at an uncontrolled rate, and feed thefwheel forward, a retractable stop to limit and control the rate of movement thereof, automaticallyoperable4 means for positively and continuously retracting rate of a directand'continuous infeedmovement of the grinding wheel, and precision mechanism for adjusting the position of the grinding wheel? without changing the position of the stop and thereby compensating for wheel wear.

13. A grinding machine comprising a base, a grinding wheelslide movably mounted'thereon, a fluid pressure "motor operatively connected to traverse said slide, a retractable stop on the base, means for positively and continuously retracting said stop at a measured rate during the wheel feed towards `the work, a contact member movable with the wheel slide in the path of the retractable stop, said member and stop being out of contact when the wheel is remote "from the work but which contact and retard the *wheel slide movement after an initial rapid infeed thereof, thereby controllingthe rate f slide movement, and adjustablemeans to vary said rate of continuous movement of the stop, whereby the grinding wheel may be fed towards the work at a continuous and controlled rate. l Y

`14.. A grinding machine comprising a base, a

work support thereon,l a` `grinding wheel -slide slide, a retractable stop movable in the path of the adjustable member and engageable with a contact on said memberfor limiting andcontrolling therate of feeding movement of the grinding Wheel towards the work,.separate power operated means for continuously retracting `the stop at a" uniform rate during the grinding operation, and manually operable separate mechanism for positioning said adiustable member relative to the wheel slide at any time, whereby the grinding wheel may be subjected to an additional feed to compensate for wheel wear without altering the position of said retreating stop.

15. A grinding machine comprising a base, a` wheel slide movably mounted thereon, a grinding wheel rotatively journalled on said' slide, a fluid pressure operated motor connected to move said slide, a nuid pump arranged to supply iluid pressure to operate said motor which tends to rapidly feed the grinding wheel towards the work, a retractable stop movable in the path of the wheel slide, a piston and cylinder mechanism connected to positively and continuously move said retractable stop, a single manually operable valve inthe iluid pressure system arranged to` set both the wheel slide motor and the retreating stop mechanism into operation, and an independently operable throttle valve connected to the retractable stop mechanism whereby said stop may be caused-,to move at a predetermined, slow, continuous, measured rate to retard and positively control the wheel feed.

v16.` A grinding machine comprising a base, a grinding wheel slide movably mounted thereon, work supporting means on the base, a grinding wheel rotatably mounted on the slide, a fluid pressure motor operatively connected totraverse said slide, a retractable stop in they path of the wheel slide movement and engageable therewith, means for` positively and continuously moving said stop at a controlledrate and adjustable., means for regulating the extent of travel oi' `said stop, whereby the grinding wheel may be caused to automatically feed towards the work at` a continuous controlled `rate for a predetermined distance. p

17. A grinding machine comprising a base, a grinding wheel slide movably supported thereon, a work supporting means on the base, a grinding wheel rotatably mounted on the slide, yieldable mechanism operatively connected to traverse said slide at a rapid rate, a retractable stop in the path of the wheel slide and engageable therewith, 1

means for positively and continuouslyI moving said stopv at a measured rate and-in the same direction as the wheel slide movement but at a slower rate,`adjustable means to limit the extent of movement of said stop relative to the work,

.said wheel slide and stop being out of contact when the wheel -is remote-from. the work, but which ultimately contact and retard the wheel slide movement and cause the grinding wheel to approach the work at a predetermined measured` rate for a predetermined distance after a rapid initial infeed thereof. t y

18. A grinding machine comprising a base, a grinding wheel slide movably mounted thereon, work supporting means on the base, a grinding wheel rotatably mounted on` the slide, yieldable mechanism operatively connected to traversersaid slide at a rapid rate, a retractable stop in the path of the wheel slide and engageable therewith, means for positively-and continuously moving said stop at a measured rate in the same direction as and simultaneously with the wheel slide movement but at a slower rate, adjustablemeans 4to regulate the rate of continuous movement of said stop, said Wheel slide and vsaid stop being out of contact when the wheel is remote from the work, but which contact and retard the' wheelv slide movement, thereby causing the wheel to approach thework at a predetermined, continuous, measured rate after a rapid initial infeed.

19. A grindi'ng machine comprising a base, a grinding wheel slide movably supported thereon, work supporting means on the base, a grinding wheel rotatably mounted on said slide, yieldable mechanism operatively connected to traverse said -slide at a rapid rate, a retractable stop in the path of the wheel slide and engageable therewith, means for positively and continuously moving said stop at a measured rate in the same direction as and simultaneously with the wheel slide movement but at a slower rate, adjustable means to regulate the rate of continuous movement of said stop, adjustable means to limit the extent of movement of said stop relative to the work, said wheel slide and said stop being out of contact when` the wheel is remote from the work, but which contact and retard the wheel slide movement, thereby causing the grinding wheel to approach the work at a predetermined, measured rate for a vpredetermined distance after a rapid initial infeed thereof.

20. A grinding machine having, incombination,

a work support, a grinding wheel, mechanism for moving the wheel into and out of the work, an abutment piece movable with the grinding wheel, a stop movable from a predetermined initial position and cooperating with the abutment piece to limit the movement of the grinding wheel toward the work, and automatic mechanism for adjusting the position of the stop during'the movement of the wheel into the work and for returning the stop to initial position during the retraction of the wheel.

21. A grinding machine having, in combination, a work support, a grinding wheel, mechanism for movingthe wheel into and out of the work, an abutment piece movable with the grinding wheel, a. threaded stop cooperating with the abutment piece to limit the movement of the grinding wheel into the work, automatic mechanism for adjusting the position of the stop during the movement of the wheel into and out of the work comprising a nut or sleeve threaded on the stop, and means for rotating the sleeve.

22. A grinding machine having, in combination, a work support, a grinding wheel, mechanism for moving the wheel into and out of the work, an abutment piece movable with the grinding wheel and-preliminarily adjustable with respect thereto, a threaded stop cooperating with the abutment piece to limit the movement of the grinding wheel into the work, and automatic mechanism for adjusting the position of the stop to control the movement of the wheel into the work.

23. A grinding machine comprising a work support, a carrier movable toward and from the work support, a rotatable grinding wheel mounted upon said carrier, power operated means for exerting a continuous yielding pressure on the carrier tending to move the grinding wheel towards the work support at an uncontrolled rate, a movable stop in the path of the carrier and engageable therewith to limit and control its movement beforetthe wheel engages the work, power operated means to cause said stop to retract continuously at a predetermined measured rate during the entir'e grinding operation to accurately control the rate and extent of feeding movement Vof the grinding wheel into the work, and adjustable means which determines the position of the grinding wheel at which its movement towards the work begins to be controlled by the stop, said adjustment having no eect on the range through which the stop may move during the grinding operation.

with a continuous yielding pressure, a movable stop in the path of movement of the wheel and arranged to retard and control the rate of wheel infeed movement prior to its grinding engagement with the work, said stop thereafter serving to resist the continuous yielding pressure and regulate the rate and extent of movement of the wheel support, and positively actuated means to cause said stop to retreat continuously at a predetermined/measured rate during the entire grinding operation and thereby accurately control the approach movement -of the grinding wheel into the work.

25. A grinding machine comprising a work support, a grinding wheel slide movable towards and from the work, power operated mechanism arranged to exert a continuous yielding pressure tending to move the wheel slide toward the work, a movable stop arranged to receive the thrust of the power operated mechanism and prevent forward movement of the wheel slide except as controlled thereby and positively actuated mechanism to retract the stop continuously during the entire wheel feed and at a constant predetermined rate and to thereby cause the grinding wheel to have a continuous controlled feeding movement, and means for varying the rate of said wheel feed.

26. A grinding machine comprising a base, a grinding wheel, a movable support therefor, a work support, yfluid pressure operated mechanism arranged to urge the grinding wheel and its support towards the work, a continuously movable stop cooperable with the wheel support to regulate its rate of approach towards the work, automatically actuated mechanism for causing the stop to withdraw continuously at a predetermined rate, thereby controlling a continuous infeed movement of the grinding wheel, and means for ,varying the rate at which the stop moves. .y

27. A grinding machine comprising a base, a grinding wheel, a movable support therefor, a work support, a fluid pressure operated wheel feeding mechanism arranged to continuously move the wheel support towards and from the work, a movable stop member cooperable with the wheel support to control its infeed movement, positively actuated mechanism to retract the stop continuously and at a measured rate during the grinding operation, means to regulate the rate of movement of said stop member, whereby the feed of the grinding wheel towards the work may be automatically controlled, and a` single controlling means to automatically return the fluid pressure feed mechanism and retreating stop mechanism to predetermined initial positions preparatory for another grinding cycle.

28. A grinding machine comprising a work support, a carrier for a grinding element mounted thereon, a movable-stop member initially 1ocated out ofA contact with said carrier, power actuated mechanism for continuously moving said stop ,slowly and positively at a predetermined grinding rate during the entire wheel feed, and a yieldable power actuated mechanism acting independently of said stop mechanism for moving said carrier rapidly in the same direction at an uncontrolled rate to overtake the moving stop and thereafter travel in contact therewith ofengagement therewith, and iluld pressure acv-W tuated mechanism independent of the carrier actuating means for positively and continuously retractlng the stop at a slow measured ,rate during the entire wheel movement, thereby controlling the rate and extent ot grinding feed after the carrier has overtaken and engaged with said stop, said carrier and stop moving simultaneously during the entire grinding wheel feed.

l y WARREN F. FRASER. v

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