US1819091A - Grinding machine - Google Patents

Description

3, 1931. w. J. GUILD ET AL 9,09

GRINDING MACHINE Filed July 25. 4927 8 Sheets-Sheet l gwwmtm (QaPclb 1 Guild.

Ralph H. Quimbq Fredflrlc Aug. 18, 1931 w. J. GUILD ETAL 1,819,091

GRINDING MACHINE Filed July 25, 1927 8 Sheets-Sheet 2 gnuenlom Waldo I GuiPcL RaPph H. Quimb Aug. 18, 1931. w. J. GUILD ET AL 1,819,091

GRINDING MACHINE Filed July 25. 1927 8 Sheets-Sheet 3 Illl (Magda I GuLLYd. Rnfph H- Qulunbn 193 I -gmmtou Aug. 18, 1931.

W. J. GUILD ET AL GRINDING MACHINE Filed July 25, 192'? 8 Sheets-Sheet 5 w O b m mmm ym W.L LG Inna 0h mp? Q fly wRF Aug, 18, 1931. w. J. GUILD ET AL 1,819,091

GRINDING MACHINE Filed July 25, 1927 8 Sheets-Sheet 6 gwoemtm 1 2? 3 a LLLm FretLrLc D. Gib

Aug. 18, 1931. w. J. GUILD ET AL 1,819,091

GRINDING MACHINE Filed July -25, 1927 8 Sheets-Sheet 7 gnwntou (1001260 I GuiEcL Ruff-i1 Frederuck D. Gibb ,1931. w. J. GUILD F a GRINDING MAcmQ.

Filed July 25, 1927 8 Sheets-Sheet 8 (100.2(10 I GuiPd.

RaPph Hummu @erick D. w t

Patented Aug. lid, i dl nnirn eras WALDO J'. GUILD, RALPH A. QUIMBY, AND FREDERICK D. GIBBS, F WORCESTER, MAS- ACHUSEI-TS, ASSIGNO 3a.:

TO THE HEARD MACHINE COMPANY, OF WORCESTER,

HASSACEUSETTS, A CORPORATION OF MASSACHUSETTS GWDEHG 1.

Application filed July 25,

The present invention relates to automatic grinding machines, of the type employed for surface grinding, and more especially where in the faces of successive small flat articles, such as piston rings, washers, ball races and the like, are sub ected to the action of a grinding wheel. More specifically the invention relates to that class .of grinding machines'disclosed, for example, in United States Letters Patent to Littman, No. 1,- 361,883, ranted December 14;, 1920, and in United tates Letters Patent to Law, No. 1,582A81, granted April 27, 1926, wherein the workpieces, stacked in a magazine, are

15 successively transferred to the grinding position and ultimately discharged from the machine by the intermittent rotation of a work carrier plate.

The invention provides an automatic 2g dressing mechanism for the grinding wheel of such a machine, together with a compensating mechanism which, in conjunction and cooperation with said dressing mechanism, regulates the amount of rinding so that successive workpieces may e round to the same commercial size. Accor mg to the invention, the dressing instrumentalities are only brought into play once during the grinding of a plurality of workpieces, and therefore a counting mechanism is provided, said counting mechanism bein actuated synchronously with the automatic transferring means for the workpieces. This counting mechanism is, of course, adjustable, to inaugurate the dressing operation at or after the rinding of any number of workpieces f om one to (for example) twenty, and the setting of this counting mechanism will depend on the hardness of the workpieces, the grade of the grinding wheel, the requirements of precision and other factors familiar to those acquainted with this art.

The invention further contemplates the application of the above principles to a machine embodying the invention described and claimedin the copending application Serial #84581, filed January 30, 1926, of Heald and Law, now Patent No.-1,681,183, wherein is shown asurface grinding machine providing. an inclined reciprocating. motion given 1927. Serial No. 208,263.

It is necessary, in order that the dressing v operation may have a size-controlling function, that the grinding wheel be dressed when it bears a known relation to the machine element which carries the dressing diamond. The present invention accomplishes this in a machine utilizing the comound, non-synchronous motion described, y temporarily eliminating one of the components and timing the dressing from this component. In other words, and being now very specific for the purpose of illustration only, the inclined reciprocating mechanism actuates the counting mechanism, which in turn controls the dressing operation, and in this way the dressing operation is made to occur at a known position of the inclined reciprocating mechanism, which is promptly put out of action till the dressing operation is completed. The only motion remaining, namely the horizontal traverse motion, effects the relative movement between the grinding wheel and the dressing device whereby the former is dressed and trued.

The above and other advantageous features of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings, in which Fig. 1 is an elevation from the right hand side of a grinding machine built in accordance with the invention.

Fig. 2 is an elevation from the left hand side of said machine, the upper part of the grinding head being broken away.

Fig. 3 is an enlarged elevation of the upper part of the machine, taken from the right hand side.

Fig. 4 is a fragmentary sectional view showing the mechanism for imparting the inclined reciprocatory motion to the grind ing head. i

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 4.

Fig. 6 is an isometric view of the table dogs that control the horizontal reciprocatory motion.

Fig. 7 is a plan view of a gear box providing transmission gearing for changing I the speed of the workholding chuck.

Fig. 8 is a vertical sectional view taken on the line 8-8 of Fig. 2 through the gear box of Fig. 7.

Fig. 9 is a front elevation of a casing containing a clutch for starting and stoppin the chuck.

igs. 10 and 11 are sectional views taken res ectively on the lines 10-10 and 11-11 of ig. 9, the former being a horizontal sectional view and the latter being a vertical sectional view.

Fig. 12 is a vertical sectional view showing the chuck spindle and the adjustable mounting of the unit which carries said chuck and the work handling mechanism.

Fig. 13 is a vertical sectional view taken on the line 13-13 of Fig. 12.

' Fig. 14 is a fragmentary horizontal sectional view taken on the line 14-14 of Fig 13.

ig. 15 is a fragmentary plan view of the compensating mechanism which is located on the right hand side of the machine.

Fig. 16 is an elevation, with the cover of its containing casing removed, of the counting mechanism of the invention Flg. 17 1s a sectional view taken on the line 17-17 ofFig. 16.

Fig. 18 is a detached view of the ratchet wheel and certain stops used in the counting mechanism.

Figs. 19 and 20 are isometric views of operating levers and associated parts.

Fig. 21 is a plan view of the dressing devlce, showing the manner of mounting it on the machine.

Figs. 22 and 23 are vertical sectional views taken respectively on the lines 2222 and 23-23 of Fig. 21.

Fig. 24 is an isometric view of a certain fluid pressure control valve mechanism.

Fig. 25 is a diagrammatic representation of the fluid pressure actuating mechanism that produces the horizontal traverse.

Fig. 26 is a wiring diagram.

Fig. 27 is a fragmentary view of a portion of the upper left hand side of the machine in order to show the relation of a captain cam to the mechanism which itopera s.

Like reference characters refer to like parts throughout the drawings.

Referring first to Fig. 1, the machine is mounted on a base 1 which provides ways, not shown, for the horizontal reciprocation and adjustment of a carriage or table 2. The carriage 2 provides inclined ways 3 for the travel thereon, in a manner that will presently be described, of a grinding wheel head 4. The grinding wheel 5 is carried by the head 4 and, as shown in dotted lines in Fig. 3 is mounted on a spindle 6 wh ich is journalled in said head. The grinding wheel may be rotated in any sultable manner; asherein shown in Figs. 2 and 3, the shaft 6 provides a drum 7 which is rotated by a motor 8, through the medium of a pulley 9 on the motor shaft 10 and a belt 11 passing around said drum and said pulley. To provide for the slight rise and fall of the head 4, due to its travel on the inclined ways 3', a heavy idler pulley 12 is employed which keeps the belt tight; the construction of these parts, being well known, need not be further describe The workpiece-holding magazine, the work carrier which successivelglflransfers individual wor ieces to grin g position, and the rotating magnetic chuck, which holds and rotates the workpiece in said position, are all carried by a se arate machine unit 13, which is mounted or vertical adjustment with respect to the base 1, on slideways 14 (see Fig. 2).

The magnetic chuck 15 is driven from the same motor 8 that rotates the inding wheel, the drive for said chuck eing as follows: Referrin to Fig. 2, the motor shaft 10 extends rom the back of the machine where the motor 8 .is located, to the front, adjacent the machine unit 13. On the front end of said shaft is mounted a bevel ear 16, shown in dotted lines in Fig. 8.

aid gear 16 meshes with a bevel gear 17 mounted on a shaft 18 journalled in a gear box 19, which is shown in section in the said Fig. 8. Gears 20, 21, and 22 of different sizes fastened to the shaft 18 mesh with gears 23, 24 and 25 rotatably mounted on a shaft 26, and by means of a sliding key 27, the power can be transmitted through any pair of gears to a pulley 28.

The position of this pulley on the machine frame 1 ma be best seen in Fi 2 while said box is s own in plan in Fig. Referring to these figures and also to Fig. 10, the pulley 28 drives a pulley 29 by means of a belt 30, said belt passing over a stationary idler pulley 31 and a spring ressed idler pulley 32, which takes the slac out of the belt and allows for vertical adjustment of the unit 13 on which the pulley 29 is located. The gear shift is operated by means of a lever 33 on the ri ht hand side of the-machine (see Fig. 1% which is connected by means of a connector 34 to a lever 35, pivoted at 36 and providing pins 37 engaging a collar 38 to which the sliding key 27 is connected.

Referring now to Figs. 9, 10, 11, a clutch is provided for stoppingthe rotation of the chuck spindle independently of the grinding wheel. To that end the pulley 29 is pro vided with a tapered internal surface. A frusto-conical member 39, which forms the other element of the clutch, is slidably keyed to a shaft and is operated by means of a lever 41 pivoted on a stud 42, said lever being connected to an operating arm 43 by means of a link 44. The arm 43 is fastened to a shaft 45 which provides a pair of yoke arms 46, 46, whose yoke pins 47, 47 fit in a collar 48 attached to the frusto-conical member 39. A spring 49 normally holds the clutch elements together.

The shaft 40 is suitably journalled in the unit 13 and has fastened to it a worm gear 50. As best shown in Fig. 12, this worm 50 meshes with a worm wheel 51 fastened to the chuck spindle 52. By these instru mentalities the speed of rotation of the chuck 15 can be controlled and said chuck can be started and stopped at will.

As already stated, the unit 13 is mounted on ways 14. Both manual and automatic means are provided for changing the height of said unit; the former so that difierent sizes of workpieces may be operated on by the machine, and the latter to compensate for reduction of the grinding wheels diameter due to Wear and dressing, as will be hereinafter set forth. Furthermore, provision must be made for inclining the face of the chuck 15 to the axis of the grinding wheel 5, so that bevelled surfaces may be ground on the workpieces if desired. To accom plish these objects the construction and mechanism shown in Figs. 12, 13, and 14 is employed, general reference being had to Fig. l which shows the relationship of these parts to the rest of the machine.

As shown in said figures, the slideways 14 are not constructed directly on the base 1, but are formed on a member 53 which is pivotally supported by a sleeve 53a extending between side plates 1a, 1a provided by the base 1. Shafts 54 and 55 likewise extend between said side plates and pass through slots 56, 56, and 57, 57 respectively in the member 53 and the side plates 1a, 1a. By means of nuts 58 and 59 on threaded ends of said shafts and pins 60 and 61 on the opposite ends, the plates la, la can be caused to press against the member 53 and hold it in any position of adjustment. Said adjustment is accomplished by means of a 55 handwheel 62 fastened to a screw shaft 63 which is held from longitudinal movement, but allowed to rotate and swivel, by means of a stud 64 which is drilled for the passage of the shaft 63, said stud engaging a shoulfifl der 65 formed on the shaft 63 and a collar 66 fastened thereto. The threaded part of the screw shaft passes through a swivel nut 67. As the stud 64 swivels in one of the side plates 1a, and the swivel nut 67 is similarly 65 attached to the member 53, it will readily be seen that turning of said handwheel will effect angular adjustment of the member 53, and consequently also of the unit 13.

Inside the sleeve 53a is a shaft 68 to the outside end of which is attached a handwheel 69. The sleeve 53a forms a journal for the said shaft which is held from longitudinal movement therein by means of the handwheel 69 and a ratchet wheel 70 at one end, and a threaded split nut 71 at the other. The sleeve 53a is cut away at 72 to allow a spiral gear portion 68a: formed on the shaft 68 to mesh with a worm wheel portion 73a formed on an upright screw shaft 73. Turning of the handwheel 69 or of the ratchet wheel 70 imparts reduced rotation to the upright screw shaft 73, and as the latter passes through a nut 74 fastened to the unit 13, said unit will be raised or lowered, as the case may he, in the ways 14. To prevent the sleeve 53a from turning or moving longitudinally and thus moving the cut away portion 72 out of position, 'said sleeve is fastened to the side plates 1w, as by means of a pin 75.

The machine of the present invention contemplates an inclined reciprocatory motion of the head 4 in order to bring the grinding wheel down upon the surface of the rotating workpiece with full face contact. It further contemplates timing of the work carrier mechanism, which is located in the unit 13 and adapted to transfer successive workpieces to grinding position, in accordance with themotion of the grinding head 4 on the inclined ways 3. The latter is described and claimed in the copending application of Heald, Heald, and Taylor, Serial No. 198,484, filed June 13, 1927, now United States Letters Patent No. 1,715,550, granted June 4, 1929, and will not be further described herein. In the present invention, however, the mechanism which actuates the head 4 is made use of to operate a counting mechanism which controls the dressin instrumentalities that periodically dress and true the grinding wheel 5 to keep its cutting periphery sharp and true and to so adjust the same relative to the surface of the magnetic chuck that uniformly ground workpieces may be produced. This actuating mechanism will therefore be described, in order that the synchronization of the machine may be understood.

Referring to Figs. 1 and 3 to 5, the driving means for the head 4 is herein shown as a motor 76 mounted on the upper ledges or plates 77, 77 of the ways 3 that are provided by the carriage 2. By means of pulleys 78 and 79 and a belt 80, the motor 76v drives a shaft 81 at reduced speed. A. worm 82 on the shaft 81 meshes with and drives a worm wheel 83 on a shaft 84, the, latter being journalled in bearings 85, 85 provided by opposite sides ofthe carriage 2. A cam 86 fastened to the shaft 84 contacts with a roller 87 which is mounted on a stud 87a carried by the head 4. At every revolution of the shaft 84 and cam 86, a cam portion 86a engages the roller 87 and so moves the head a slight distance up the inclined ways 3. In order to compel the roller 87 to follow the periphery of the cam 86 closely, and to overcome any friction of the head 4 on the inclined ways 3, a spring 88 is provided. Said spring is supported on a rod 89 carried by the head 4 and on another rod 90 carried by the carriage 2. The rod 90 has a reduced portion 91 which fits in the internal diameter of the spring and by reducing the diameter in this way a seat is formed for the spring to act against. The other end of the spring thrusts against a boss 92 provided by the head, 4. The amount of pressure exerted by the spring 88 is adjustable, as the rod 90 is screw threadedat the end opposite the reduced portion 91 by which it is adjustably attached to the carriage 2.

To the opposite ends of the shaft 84, outside the journals 85, 85 and consequently on opposite sides of the carriage 2, are fastened cams 93 and 94. The cam 94 actuates a valve 95 (see Figs. 2, 25 and 27) which controls fluid pressure actuation of the work carrier mechanism. The cam 93 is adjustably fastened to a disc 96 keyed to the shaft 84, by means of slots 97 in the said disc and bolts 98 screwed into the same cam, and said cam actuates the counting mechanism heretofore referred to. Tothat end a lever 99 provides a roller 100 and a coil spring 101 surrounding the hub of the lever, compels said roller to follow the periphery of the said cam 93.

The pivotal stud 102 that supports the lever 99 is carried by the carriage 2. The lower end of the lever 99 is connected by a bar 103 to anarm 104, whose pivotal stud, 105, is also carried by the carriage 2 and is located at the same height as the stud 102. The length of these parts is such that lines drawn between the studs 102 and 105 and the points of pivotal connection of the bar 103 to the arm 104 and the lever 99 form a parallelogram, so the bar 103 is always horizontal. Downward movement of the bar 103 actuates the counting mechanism, which is located on the machine base 1 and which will be described in detail hereinafter.

As already stated, the presentation of the workpieces to the grinding wheel 5 is operated synchronously with the travel of the head 4 on the inclined ways 3. This travel of the head 4 gives the grinding wheel 5 an inclined, intermittent, reciprocatory motion. It is necessary, however, to provide means for reciprocating the grinding wheel in a horizontal plane, for two reasons. The first is that if the wheel 5 did all the grinding at one place across its periphery, a groove would be worn in the wheel. The second is handles 126, 126, provided by that the grinding wheel must be withdrawn from the work in order that it may be dressed and trued, and such withdrawal must be parallel to elements on the cylindrical periphery of the wheel, which in this case are horizontal.

As shown in Fig. 5, the carriage 2 provides sliding surfaces 106 and 107 which rest on horizontal slideways, not shown, provided by the machine frame 1. Referring to Fig. 25, the means for reciprocating the carriage 2 is illustrated herein as a fluid pressure actuating system. As shown in said figure which is diagrammatic-as to the position of the arts, fluid under pressure may be supplied, for example, by a pum 108 from which the fluid is led, by way 0 pi ing 109, to a reversing valve 110. The mounted in a valve-casing 111 and is connected, by connections not shown, since the construction and operation of fluid pressure reversing mechanism is now well known in this art, to a reversing lever 112, pivotally mounted on the front of the machine.

Fig. 1.

In the position of the reversin valve shown in Fig. 25 the pressure uid is admitted by way of a port 113 and piping 114 to the left hand end of a cylinder 115, in which is located a piston 116, whose piston rod 1160: is attached to the carria e 2. The fluid under pressure, acting on t e piston, moves the carriage 2 to the right, Fig. 1, in which direction it continues, the fluid exhausting from the ri ht hand end of the cylinder 115 by way 0 piping 117 and c linder port 118 and exhaust port 119, unt' the reversing valve is moved to connect the port 118 to the fluid supply pipe 109, and port 113 to the exhaust port 119. This brief description of the carriage actuating mechanism will suflice for an understanding of the present invention, and as far as the latter is concerned, any other type of actuating mechanism might be substituted.

Referrin now to Fig. 1, the reversing lever 112 is operated from the carriage 2 through the medium of spaced adjustable dogs 120 and 121 carried thereby. The left hand dog 121, unlike the right hand dog 120,

is a pivotally mounted dog, being carried by a pin 123 provided by a block 124 which, the same as the carrying block 125 for the right hand dog, is ad ustably fastened to the carriage 2, as by means of tightenin bolts with th blocks 124 and 125. See Fig. 6. Means is provided to lift the said left hand pivotally mounted dog 121 in order that the carriage 2 may continue its travel to the right to atter isbring the grinding wheel 5 in contact with a dressing device 127. As this means is actuated and controlled by the counting mechanism heretofore referred to, said mechanism will now be described.

Referring to Fig. 1, said counting mechanlsm is contained in a boxer casing 128 mounted on theri ht hand 'sideof the machine frame 1. 'S aid casing provides upwardly extending bracket arms 129, 129, which support a shaft 130. The shaft 130 -constitutes the pivotal support for a number of levers which are shown in Figs. 16 and 17, and in isometric view in Fig. 19. Adjacent the inner bracket or arm 129 on the shaft 130 is mounted a lever 131 which provides a roller 132 engaging the under surface of the bar 103, which, as has been already described, is moved downwardly once during every reciprocation of the head 4 on the inclined Ways 3.

The lever 131 is connected to an arm 133, located in the casing 128, by means of a link 134. The arm 133 is pivotally mounted on a shaft 135 which is journalled at 136 and 137 in the casing 128, and the arm 133 provides a spring pressed pivotally mounted pawl 138 which is adapted to engage the teeth of a ratchet wheel 139 fastened to the hub of a cam member 140, which is likewise rotatably mounted on the shaft 135. Normally the arm 133 is held in its upper position, as shown in Fig. 16, with an adjustable stop 141, shown in the form of a screw, abutting a boss 142 on the inside of the casing 128, being held there by means of a spring 143. In this position of parts the spring pressed pawl 138 is held away from the ratchet wheel 139 by means of a pin 144. When, however, the arm 133 is depressed by downward movement of the bar 103 and the connections described, the pawl 138 moves into engagement with the ratchet wheel 139 and rotates the latter through the distance of one tooth.

This counterclockwise movement of the ratchet wheel 139 is opposed by a coil spring 145 which surrounds part of the hub of the cam member 140, one end of said coil spring being fastened to a pin 146 provided by the casing 128, and the other end being secured to the said cam member. Retrograde movement of the ratchet wheel is normally prevented by means of a hold pawl member 147 pivoted on a stud 148 in the casing 128 and urged against the ratchet wheel by means of a coil spring 149, the ends of which are fastened respectively to said giawl member and to a stationary pin 150. ee Figs. 16 and 20.

The cam member 140, which to all intents and purposes, is integral with the ratchet 139, is for the greater part of its periphery circular in form, but provides a cam projection 140:; which, when moved into engagement with a roller 151 provided by an arm 152, (see Figs. 16, 17, and 20), causes 3 an opening of the electric circuit which runs the motor 76 that gives the head 4 its motion on the inclined ways 3, and also causes the pivotally mounted dog 12]. to be lifted on the next right hand movement of the carriage 2, thereby to effect the dressing and truing of the wheel 5. a

V The arm 152 is pivotally mounted on the same stud 148 which holds the hold pawl 147, and said arm 152 is likewise provided with-a coil spring 153 to urge 'it upwardly, one end of this coil spring being attached to the pin 150. The left hand end of the arm 'on the shaft 130. The lever 161 provides an inclined surface 162" which'is in the same vertical plane as, and normally ust below,

the pivotally mounted dog 121, when, by

the downward movement of the arm 152, the link 160 is also drawn down, the right hand side of the lever and consequently the inclined surface 162, is raised, and this brings'the latter into the path of the said table dog 121, so that as the carriage 2 next travels to the right, the dog lshfted clear of the reversing member 112 and the carriage continues its movement to the right.

This amplified right hand movement of the carriage 2 occurs when the head 4 is at its extreme left and downward posltlon on said carriage, this being insured by the stoppage of the motor 76 and by reason of the fact that such stoppage 1s occasioned responsive to actuation of the train of mech anism which moves the cam 140a and which ultimately derives its motion from the cam 93, the latter, as previously described, being fastened to the same shaft 84 that carries the grinding head operating cam 86. VVithdrawal of the carriage 2 to the right, therefore, takes place with the axis of the grinding wheel 5 located at a known and fixed elevation in respect to the machine base 1, and said withdrawal carries said wheel across the dressing point 127, located, as will now be described, in the unit 13.

Referring to Figs. 21, 22 and 23, the dressing device 127, preferably a diamond, is mounted in a plug 163 and suitably fastened in a screw threaded holder 164 which is carried by another member 165, the latter being screw threaded internally for the reception of the holder 164 and externally in order that it may be adjustably held by a boss 166 providedb the chuck surrounding pan 167 that forms part of the unit 13. A lock nut 168 is provided to prevent accidental displacement of the holder 164 in the member 165. The latter provides a pointer 169 integrally connected to it, the end of which is adjacent a graduated plate 170, said plate of force it will hold it against-vibration or an accidental hitting of thepointer. The

amount of pressure exerted on the plug 171 by the spring 172 is governed by means of a screw plu 173.

After eac dressing of the wheel 5 in response to the amplified reciprocation of the carriage 2 to the right it is obvious that said wheel will be tangent to a plane containin dressing point 127. Subsequent to sue dressing action which, as already stated, occurs only intermittently, after a predetermined number of workpieces have been ground, the grinding wheel in operatin on the next lot of workpieces will have been reduced in diameter by wear, to a certain extent at least. Consequently, in order that the next succeeding movement of the wheel 5 over the dressing point 127 may result in the removal of some material from said wheel in order to true its periphery, it is necessary to raise said dressing point between each successive dressing operation.

This is accomplished in the present machine just prior to the actual dressing contact, and takes place in the following manner.

Referring to Figs. 1, 6 and 19, a block 174 also adjustably fastened, as by means of a bolt 175, to the carriage 2, provides a cam bar 176 with an inclined surface 177. Said inclined surface on the right hand movement of the carriage 2 engages and depresses a roller 178 carried by a lever 179 pivotally mounted on the shaft 130. This action takes place before contact between the grinding wheel and the dressing diamond. The left hand end of the lever 17 9, as best shown in Figs. 16, 17, and 19 provides a fork portion 180 which surrounds a pin 181 provided by a lever 182 mounted on a stud 183 carried b the machine base 1. See Figs. 1 and 15. he left hand end of the lever 182 is connected by means of a link 184 to an arm 185, which is pivotally mounted on the sleeve 53a. Downward movement of said arm 185, responsive to engagement of the inclined portion 177 with the roller 17 8, moves a pivotally mounted spring pressed awl 186 into enga ement with the ratchet wheel 70, thus rotating the latter slightly in a clockwise direction. This movement of the ratchet Wheel, as previously described, causes the whole unit 13 to be raised. This action,

therefore, compensates for the reduction in diameter of the grinding wheel 5 and for the previous dressing of said wheel, and compensation is adjustable in amount in the following manner.

The lever 182 is normally urged in a clockwise direction by means of a coil spring 187 surrounding its hubandaattached at one end to the lever and at the other to a stationary pin 188. This action holds the arm 185 in its upward position, as determined by a stop arm 189 having an overhan 'ng engaging portion 190, sald arm provi ing a split hub 191 surrounding the sleeve 53a and adapted to be tightened thereto to any position of adjustment, as b means of a tightening screw provided wit a large knob 192. The initial osition of the pawl 186 being thus adjusta 1e and the point to which it is moved being always the same, by reason of the invariable action of the inclined surface 177 on the roller 178 and the various connections, said pawl can be caused to move the ratchet through a distance of one or more teeth thereof, as desired.

The cam member 176 has another function'which is performed subsequent to the action just described and this is to reverse the direction of travel of the carriage 2, which it does by striking and shifting the reversing member 112. This causes movement of the carriage 2 to the left, Fig. 1, whereupon the pivotally mounted dog 121 lifts over the said reversing member 112 and the carriage 2 resumes its normal reciprocations to create a traverse between the wheel 5 and the workpieces.

This retrograde movement of the carriage 2 restores the ratchet wheel 139 to its original initial position in the following manner. On the outward or right hand movement of the carriage 2 a pivotally mounted member 193, carried by the block 124, is engaged by a roller 194 on a lever arm 195 which is =pivotally mounted on the shaft 130. This contact produces no action except to swing the member 193 to allow it to pass over the said roller, but upon subsequent left hand movement of the carriage 2 an inclined surface 196 on the said member 193 re-engages said roller 194 and depresses it, since the member 193 cannot swing to the right further than the vertical position shown in Fig. 6, by reason of a stop projection 197 provided by the block 124. Depression of the roller 194 movesthe lever 195 in a counterclockwise direction and this action depresses the pawl arm 147 by reason of the fact that said arm is connected to the lever 195 by a link 198. Depression of the pawl arm releases the ratchet wheel 139,

whereupon the latter revolves in a clockwise directionunder the influence of the spring 145.

The ratchet wheel 139 and consequently also the cam 140 come to a stop when a pin 199 carried by one of these parts engages-- 'a pin 200 projecting from a cylindrical flange 201 provided by the shaft-135. See Figs. 16, 17, and 18. As the position of the ratchet wheel 139 when the pawl arm 147 is moved downwardly to release said ratchet wheel is a fixed position, the position of the pin 200 therefore determines the amount of clockwise rotation of said ratchet wheel, and consequently by adjusting the position of the pin 200, the angular movement of the ratchet wheel between dressing operations can be controlled. It will be remembered that the dressing operation is inaugurated by movement of the cam 140 to a certain angular position. This adjustment, which determines the number of workpieces that will be ground between successive dressing operations is accomplished in the following manner.

The cylindrical flange 201 abuts against the right hand journal 137 and by means of a nut 202 on the front of the shaft 135, which presses against an interposed indicator dial 203, the flange 201 can be drawn solidly against the journal portion and thus the shaft made nonrotatable. By'loosening the nut 202 the pin 200 can be turned to any desired position by rotating the shaft 135,

the front end of said shaft being slabbed off to allow the use of a wrench for this purpose. Since the dial member 203 is keyed to the shaft 135, it will be readily seen that said dial can be graduated to read directly the number of interposed grinding operations between successive dressing operations, said dial being read by means of a stationary mark 204 provided on the outside of the casing 128. See Fig. 1. v

It is highly desirable that the amplified ri ht hand travel of the carriage 2 which su lijects the wheel 5 to the action of the dressing device 127 should take place at a, rather slow speed, in order that the dressing operation may not result merely in agroove being made in the wheel. To that end the machine of the present invention provides a valve member 206 (see Figs. 24 and 25) which, when turned, is adapted to restrict the flow of fluid through the supply piping 109. As shown in Figs. 1 and 24, the carriage 2 provides a fourth ad ustably mounted block 207 which has an inclined surface 208 that engages and depresses a roller 209 'ust prior to contact between the grinding w eel and the dressing device. The roller 209 is provided by an arm 210 fastened to a rotatable shaft 211 suitably jour nalled in the machine frame 1. The opposite end of said shaft 211 has fastened thereto a depending arm 212- which is connected, as by means of an adjustable link connection 213, to an arm 214 fastened to the rotatable valve member 206. WVhen the roller 209 is depressed, the valve 206, by reason of the connections described, is turned, and the speed of the carriage 2 is checked. A coil spring 215 fastened to a stationary pin 216 and the arm 210 restores these parts to initial position to permit full speed actuation of'the carriage 2, just as soon as the block 207 moves away from the roller 209.

We claim:

1. In a grinding machine, the combination with a grinding wheel, having means for re ciprocatin'g it in an inclined plane, and automatic means to dress and true said grinding wheel during cessation of its inclined movement, of a counting mechanism actuated synchronously with said reciprocating means, said counting mechanism being adapted to set the automatic dressing means in operation after the grinding of a predetermined number of workpieces.

2. In a grinding machine, the combination with a grinding wheel, means for reciprocating said grinding, wheel in an inclined plane, means for reciprocating said grinding wheel in a horizontal plane, said latter means being compounded with said first named means, of means for causing cessation of one of said reciprocating means at a determinate point, and further means for causing the other of said two reciprocating means to withdraw the grinding wheel across a dressing device, thus dressing and truing the grinding wheel to a known depth.

3. In a grinding machine, the combination with agrinding wheel, means for reciprocating said grinding wheel in an inclined plane, means for reciprocating said grinding wheel in a horizontal plane, said latter means being compounded with said first named means, of means for causing cessation of said inclined reciprocating means at a determinate point, and further means for causing the horizontal reciprocating means to withdraw the grinding wheel across a dressing device, thus dressing and truing the grinding wheel to a known depth.

4. In a grinding machine, the combination with agrinding wheel, means for reciprocating sai grinding wheel in an inclined plane, and entirely independent means for reciprocating said grinding wheel in a horizontal plane, said latter means being compounded with said first named means, of means under the control of one of said reciprocating means for procuring the dressing and truing of said grinding wheel, and means to stop one of said reciprocating means during the said dressing at a predetermined point.

5. In a grinding machine, the combination with a grinding wheel, means for reciprocating said grinding wheel in an inclined plane, and entirely independent means for reciprocating said grinding wheel in a horizontal plane, said latter means being compounded with said first named means, of a work rotating chuck, and means for procuring the dressing and truing of said wheel to bring its periphery to a known relation to said chuck.

6. In a grinding machine, the combination with a grinding wheel, a rotary chuck, means for reciprocating one of said parts relative to the other, anda dressing device located a fixed distance above said chuck but beyond the normal relative path of reciprocation of said wheel, of means for extending said relative reciprocatory travel, and compensating means brought simultaneously into operation for raisin said chuck and said dressing device, where y to dress and true said wheel to a known relation to said chuck.

7. In a grinding machine, the combination with a grinding wheel, means for recip: rocating the wheel in a direction parallel to the cutting line of wheel and work, means for reciprocating said wheel in a direction inclined to said first named direction, the first named reciprocating means serving to remove grinding lines in the work, and the second reciprocating means serving to cause full-faced initial grinding contact, the aforesaid reciprocations being compounded into each other, of means for causing the grinding wheel to be dressed and trued to maintain the same cutting line comprising'means for stopping the second named reciprocating means at a predetermined point, a dressing device, and means for causing the first named reciprocating means to withdraw the grinding wheel across said dressing device, thus dressing and truing the grinding wheel to a known depth.

8. In a grinding machine, the combination with a grinding wheel and means for reciprocating said wheel in a direction inclined to the cutting line of the wheel and work in order to cause full-faced initial grinding contact, of a dressing device, means or causing relative motion between said grinding wheel and said dressing device in a line parallel to the line of cutting contact of wheel and work and therefore at an angle to the first named reciprocating means, and means for stopping said wheelreciprocating means, thereby to permit the operation, without interference from said wheel-reciprocating means, of said means that causes relative motion between the grinding wheel and the dressing device.

- WALDO J. GUILD.

RALPH A. QUIMBY. FREDERICK D. GIBBS.

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