US1901236A - Grinding machine - Google Patents

Description

March 14, 1933.

w. J, GUILD GRINDING MACHINE Filed Jan. 11, 1929 5 Sheets-Sheet 1 jnuq'ufoz (A) lcLo 3 GuLLCL March 14, 1933.

W, J. GUILD GRINDING MACHINE gwuemtoc waldo I Guu L March 14, 1933. w; 1 GUILD 1,901,236

GRINDING MACHINE Filed Jan. 11, 1929 5 Sheets-Sheet 3 (101m 1 Guild.

March 14, 1933. w GUILD 1,901,236

GRINDING MACHINE I Filed Jan. ll, 1929 5 Sheets-Sheet 4 'llllllllllllllllllllllllllllllllllhllllllllllllllllllllllllllllillllllllll H 757- 5 womb. :r. GIILICL m/fg attozww p to avoid interference:

Patented Mar. 14, 1933 UNITED STATES PATENT 0 WALDO J. GUILD, or woncnsrna massacnusnr'rs, Assronon To run HEALD MACHINE comm, or woncnsrnn, mssacnusnrrs, a conronarron or massacnusnr'rs Gamma MACHINE Application filed January 11, 1929. Serial No. 331,838.

The invention relates to grinding vmachines adapted for the external grinding of small objects such as roller bearing race ways, and in certain aspects the invention is one of improvement onvthe grinding ma-. chine of Heald et al. Patent No. 1,841,809, datedJanuary 19, 1932, although many features of the present invention might be applied to other and difle'rent machines.v

In the operation of automatic 'or semiautomaticmachines, such as that shown in the aforesaid patent, in-which several machine elements work in timed relation with each other, it is of vital importance that each of the elements come into operating.

position at precisely .the right time in order Especially is this so in machines that involve purely mechanical means for operating some of the moving parts and hydraulic means for operating other parts.

In such a machine the mechanical elements derive their power from a. prime mover, such as a motor, while the hydraulic source of pressure such as a pump, which in turn derives .its power from a separate source. Where the separate prime movers are independent of each other, or where the mechanically actuated elements merely set in operation the hydraulic mechanism, it w ll be readily seen that if the source of power to the pump fails the hydraulic elements will stop in their cycle without afli'ecting the continued action of the mechanical elements, and under certain conditions the continued action of the latter will cause damage to the this invention as applied .to a grinding machine having a work carrying slide, operated by "mechanical :means, and two wheel supporting tables or carriages, eachmoyed in a caused to move by elements derive their power from a suitable cycles before .the

slide to predetermined sequence to the other, and

hydraulically actuated in timedsequence to the work carrying slide.

As. amachine having two types of mechanisms which obtain their motion and power from different sources presents the problems above outlined, another object of this inven tion is to make the two main sources of power interdependent in. such a mannerthat when one mechanism has performed its cycle or cycles it will cause the other mechanism to start through its own cycle, whereupon the movement of the first mechanism is arrested until the completion of the cycle of the second mechanism, at which time the first mechanism is caused to again start through its cycle or cycles.

drawings provides ashaft which has a cam on one end for operating the vertical slide,

FFICE i he grinding machine as shown in theand a cam on the opposite end to cause mechan1sm in a counting box to operate a piston valve whereby the. wheel carrying tables'are hydraulic pressure. The go through one or more wheel carrying tables or carriages are caused to move by the hyvertical slide may draulic means, the number of cycles between movements of the wheel carriages being governedby the setting of the counting mechanism. -When the wheel carriages/start tomove one of an alternate pair of circuits is broken but the work carrying slide cam continues to revolve until it is approximately on the point of causing the work carrying descend, whereupon theiother circuit is broken thus stopping the cam from further movement by cutting oil the power to its driving motor. The wheel carriages continue through'their cycle and on completion thereof the first circuit to be broken is, again made, starting the motor, and the work slide can] startsto revolve allowing the said slide 1 toagain go through its cycle or cycles.

It will thus be seen that the mechanical elements are responsible for the putting into operation of the hydraulic mechanism butthis in no wise interferes with the action of the two mechanisms, owing to the fact that having put the hydraulic mechanism in motion said mechanical elements thereupon put themselves under control of instrumentalities operated by said hydraulic mechanism.

In a machine in which the movements of is disproportionately long in relationto the time needed to complete the balance of a. single cycle of operation, it has been found desirable to periodically slow down the speed of rotation of this operating cam in order that the machine-may operate at its maximum speed during the remainder of the cycles This slowing down also makes it possible to use an automatic device for feeding the work to the spindle, as there is a definite, period of time required by such a device within which it can function efliciently, and this period is invariable regardless of the speed of the rest of the machine.

In other words there 1s a certain portion of the cycle of operations that must ,be a" of the cycle and it is another object of this invention to provide electrical means in the form of a cat deal slower than the, rest rheostat, automatically placed in serieswith the field circuit of an adjustable speed direct -.ably received within the spindle 5, the workcurrent motor,by means of a switch actuated v bythe mechanically operated element, to cause the said element to slow down to allow time for loading and unloading.

grinding machines there is a wearing away of the wheel due to grinding and dressing, and there is a point in the reduction of the diameter of a grinding wheel beyond which it is inefiicient to go, due to the fact that the surface speed of the pvheel becomes less as its diameter diminishes when run at a given number of revolutions per minute. Stated'in another way, when a new wheel of the required diameter is-run at a surface speed proper for its'size, its diameter can be reduced only by a given amount before its cutting efliciency is lost, and when that amount of reduction has been made it is .necessary to change the wheel.

grinding wheel is reduced to too small a diameter, there is danger of spoiling the workpieces, and also some means is not provided to stop the rela tive feed between work and wheel when the latter has become reduced to a predetermined size. In view of the above conditions to be coped with in the operation of on an automaticgrinding machine, the present invention provideselectrical means to interrupt the functioning of the machine as soon as the wheel reaches its smallest allowable diameter.

When the v the wheel spindle itself, if

I A still further object of this invention is to operate the work chuck by means of a hydraulic unit under the control of the mechanically operated mechanism, thereby in suring the releasing and gripping of the work being accomplished in. a positive manner at the correct time. J

.Further and ancillary scope-of this invention will be apparent from the following detailed description taken in connection with the accompanying drawin%, in w ich;

igure 1 is a front elevation of a grinding machine constructed in accordance with the present invention,

Figure 2 is an side of the said machine.

Figure 3 is a plan view of the machine. Figures 4 and 5 are fragmentary elevations of the grinding wheel heads of the maobjects within the Y J I elevation of the left hand chine, together with the tables or carriages upon which they are mounted. F'gure 6 is a fluid pressure diagram.

Figure 7 is a wiring diagram.

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

The machine, is mounted upon a suitable frame 1 and provides a workhead 2 carried by a slide 3, which is adapted to be vertically reciprocated in slide waysA provided bythe frame. Journalled in the workhead 2 is a work carrying spindle 5; by means of an expansible collet 6,, actuated by a rod 6a slidbe clutched to and released from The rod 6a may be actuated automatically aswill hereinafter appear. Referring now to Fig. 2, the work spindle 5is rotated from a pulley 7 by means of a belt 8 which asses around said pulley and a pulley 9 astened to the spindle. By means of an adjustable tightener 10, which is held against the belt 8 by means of a heavy spring, not shown, the belt is kept at constant tension despite the rise and fall of the slide 3.

The workhead 2 is given a vertical reciprocatory positlon, in order that ground workpieces may be removed from the work spindle 5 and unground workpieces placed thereon. The lower position is the grinding posit on, and the upper position is the work changing POSI- tion, as already explained, the spindle dwells ,at the upper position, and the expandmg and contracting collet 6 is contracted at that time, whileas will be hereinafter described, automatic means is provided to stop the rotation of the spindle 5 long enough so that the ground workpiece may be readily r emoved and anunground one placed 1n pos1t 1on.

Referringnow to Fig. 2, the machme provides a motor11, the shaft of which provides a pulley 12 which, b drives a pulley 14.

pieces may the spindle.

aid pulley 14 is fasmotion with a long dweltat the upper means of abelt 1 7 cycle of the machine,

this cam causes the vertical reciprocation of the slide hereinbefore mentioned. These parts canbe seen in Figs. 1 and 2. The pres ent machine being shown as an improvement on the machine of the aforesaid Heald et a1. patent is also adapted to'ha've incorporated thereinto an automatic work loading macha. nism such as that disclosed in'the copending application Serial N 0. 359,617 of Ralph A. Quimby, filed May 1, 1929. Whether automatic work loading mechanism of this or any other type is used in connection with this machine or not, it is desirable that the slide 3 should be at its upper or work loading position for a substantial and determinate period of time during each phase in the cycle of operation of the machine intended for the change of workpieces. This is so because even in the case of workpieces changed manually, a suflicient length oftime must be allowed for the proper accomplishment of this change; a large dwell has been shown on the cam 22, but this is'not sufficient, for the reason that under varying conditions the ma chine may be run at different speeds, and therefore this dwell, while representing a definite fractional amount of the complete would nevertheless-represent different periods of absolute time. The present invention, therefdre, contemplates means for lengthening this period of dwell which will now be described.

Referring to the wiring diagram of Fig. 7, 25 and 26 are electric current power mains; the former connects directly one armature brush of the motor 11, while the other brush is connected to the main 26 via a switch 27 and lead 28. The field coils of the said motor, are shunted into these mains, and in series with them is a rheostat 30 which, however, can be cut out of the field coil by means of leads 31- and 32 terminating in contacts which are adapted to be closed by a switch 33.

The switch 33 is normally closed in order that the current may pass through the field coils of the motor unimpeded by the resistance offered by the rheostat 30, but when the slide 3 has substantially arrived at its upper or work loading position, an adjustable screw 34, carried by an arm 35 attached to theslide, engages a button 36 provided by the switch and opens the circuit through the leads 31 and 32," thus compellin the current to flow through the rheostat 30 and therefore causing the motor to be slowed down to a regulated adjustable speed.

Referring now to 3, the machine provides a 'grinding'wheel 37 adapted to grind a cylindrical or conical surface a on each of the several workpieces uponwhieh it operates. wheel 37a adaptedto grind a flat or conical surface on the workpieces, such as an under cut portion on a flange b. To these ends the grinding wheel 37 is carried by a wheelhead 38 which, inthis embodiment of the invention is a motor, said wheelhead or motor being angularly and horizontally adjustable,

and transverse feeding means being also pro-' vided to adjust the grinding wheel to the size of the workpieces and to compensate for wear and tru-ing by-dressing, as will be hereinafter described. The grinding wheel 37a is carried by a wheelhead or motor 38a which, as in the case ofthemotor 38 is angularly and horizontally adj ustable and can be positioned relative to the work by transverse feeding means. Additionally, however, the wheelhead 38a is given a regular reciprocating motion on the line of said transverse feed, in order that the aforesaid flange b be not de stroyed when the workhead rises. y In the respects just enumerated, the machine does not differ in' any material manner from that of the Heald et=al. patent hereinbefore referred of dressing is inaugurated in the interval between grinding of successive workpieces, or only after a predetermined plurality of work pieces have been ground, according as a certain counting mechanism to be described is set. Referring now to Fig. 4, the wheelhead 38 is mounted upon a cross slide 39 that is slidable in transverse ways, not shown, pro vided by a table or carriage 40. Said table 40 provides journals or bearings for a screw shaft 41 which passes through a nut, not shown, attached to the cross slide 39, and by turning the screw shaft 41 said cross slide and conse uently the wheelhead 38 may be fed towar or away from the axis of rotation of the workpiece- The table 40 is in turnslidable longitudinally in ways 42, Fig. 2, provided by abase 43, the latter being an-. gularly adjustable upon the machine frame 1 as fully described in the aforesaid Heald et al. patent.

In similar fashion, the wheelhead 38a is mounted upon a cross slide 39a that is slidable transversely in ways, not shown, provided by a turret 44. The latter is carried by a table 40a that is, in turn, slidable in longitudinal ways provided by a base 43a which,

The-machine also provides a grinding 45 derlying bases as in the case of the base 43, is angularly adjustable upon the frame 1. A screw shaft 41a is provided to position the cross slide 3941 transversely of the turret and consequently 5 on a line which bears a variable angular relation to the table or carriage 40a. The'mount:

ing of the separate motor wheelheads 38 and "38a upon the machine has, been only briefly described herein, since the construction practically follows that of the Heald et al. patent aforesaid, and the present invention relatesto the control of the reciprocatory movement of the several tables or carriages, including the vertically reciprocable carriage or slide 3, together with other features, as already in- I dicated, which will be described in detail, and

so far as the present invention is concerned any desired construction of tables or carriages and cross slides mlghtvbe substituted forthat herein shown.

done in order to keep the said grinding wheels sharp and free cutting and to preserve-the proper contours thereof, the necessity of which in the grinding of workpieces having flanges b and c as shown in Fig. 3,]will be readily apparent to those skilled in this art.

Besides these reasons for dressing, the machine of the present invention, like that of the aforesaid Heald et al. patent makes use of the dressing operation to maintain the cutting surfaces of the grinding wheels in a known plane; by the movement of separate workpieces tangentially in respect to the grinding wheels to grinding positlon uniformity of the finished prodiict is secured.

The dressing. operations consist in relative motionbet-ween grinding wheels and dressing devices, and in the present machine 'it is, found convenient to move the grinding'wheels past the dressing devices mounted on the un- 43 and 43a, and the reciprocable tables and 40a are provided for this purpose. Naturally the reciprocations of carriages 40 and 40a which cause theflgrinding wheels to be trued, must take place when the work carrying slide 3 is in its upper position, since the grinding wheel 37, during the grinding operation, is located between the flanges b and c on the workpiece and to move it in" a direction parallel to its axis would result in cutting off one or the other of said flanges. Also the equally obvious necessity of preventing the moving of a workpiece into grinding position until the wheels 37 and,37a have fully resumed their original grinding positions, requires the positive and fool-proof synchronization of the motions of the three tables, carriages, or slides, whichever they be termed, 3, 40, and 4( )a Before describing the means for moving the'tables 40 and 40a and the various means of control therefor and of synchronization of these three tables, I

the apparatus for causing the dressing opercam is shown in Fig; 6 located in a box-like structure 45 that is provided on the back of the machine. Once during each revolution of the cam 44 it depresses a roller 46, carried by a lever 47 pivoted at 48 to the machine frame. An arm 49, pivotally mounted on a shaft 50, is connected by means of a link 51 to the lever 47, and consequently the lever and arm move together, the arm 49 providing a spring 52 whichtends to raise these parts and to keep the roller 46 against the periphery of.

the cam 44. Pivotally mounted at '53 on the arm 49 is a pawl 54, which is pressed by means' of an internalspring, not shown, reacting against the pivot stud, toward a'ratchet wheel '55, which is mounted on the shaft 50. -Except when the parts are drawn downwardly,

the awl 54 is kept from contact with the rate et wheel by means of a pin 56, but when the pawl moves downwardly, it is allowed to contact the ratchet wheel by reason of configuration of said pawl, and the motion im- I parted to the ratchet wheel is just sufficientto move the latter by the distance of one tooth.

As indicated in dotted linesin Fig. 6, and as illustrated more completely in the aforesaid Heald' et al. patent, theratchet'wheel 55 is fastened to a cam member 57 mounted on the shaft 50. Counter clockwise movement of the ratchet wheel in response to the actuations of the pawl 54 is opposed bya coil spring, not shown herein, which sur-' rounds part of the hubof the cam member 57, one end of said coil spring being fastened to a stationary part of the casing 45 and the other end being secured to said cam member.

However, retrograde or clockwise movement of the ratchet wheel 55 is normally prevented by means of a hold pawl member, 58, pivoted on a'stud 59 in the casing 45 and urged against the ratchet wheel by means of a compression spring 60.-

The cam member 57, which to all intents and purposes is integral with the ratcheti55, is for the greater part of itsperiphery circular in form, but provides a cam projection 61 which, when moved into engagement with a roller 62, provided by a lever 63 pivoted on the aforesaid stud 59, moves said lever clockwise against the tension of a spring 64. This action inaugurating the dressing operations, causes movement of the tables 40 and 40a in the following manner.

Referring to Figs. 2 and 6, the machine proing adapted to create a pressure on a suitable and 77a carried by g5 fluid such as oil, and said pump being driven desirably byan electric motor 66. From the discharge end of the pump the fluid is led by piping 67 to an entrance port 68 in a valve casing 69. In the valve casingis a slide valve 70, which is connected at 71. to the lever 63.; In one position of the valve member 70 (the position shown in dotted lines) the'pressure fluid is admitted to piping 7 2, which branches into two parts 73 and 73a that lad'to theright hand end of cylinders 74 and 74a. v( The cylinders 74 and 7411 are considered to be viewed in the position in which they would appear were they shown in the views of Figs. 4 and 5, and in which fluid admittedto the right hand end of the cylinders, as viewed in sald'figures, tends to urge the said tables to the left and 'vice versa.) Said cylinders are located in the- bases 43 and 43a respectively,

'and contain pistons, not shown, connected by.

pistonrods 75 and 75a to the tables or barriages and 40a respectively. Y

In the position ofparts shownin Fig. 6 which is the normal condition, the pressure fluid is made active against the right. hand end of each piston, holding both carriages to the left so as'to maintain the grinding wheels 37 and 37a in contact with a workpiece or at least in position .for immediate grinding. Aceurate positioning of the tables is obtained by-stops 7 6.and 76a located on the bases 43 and 43a, and co-operative adjustable stops 77 the tables '40 and 40a respectively. C. 1

When, as already stated, the left hand end 6 of the lever 63 is raised, the valve member 70 is lifted, which disconnects the piping 72 from the pressure supply port 68 in the valve' casing 69, and'connects it instead to an exhaust port 78, and at the same time allows the pressure fluid to flow from the supply port 68 into a pipe 79that is adapted to supply fluid to'the left hand endsof both cylinders 74 and 74111 To that end'the pipe 7 9 branches into pipes 80 and 80a respectively, through thelatter 0 which the fluid immediately flows by way of a valve port 81 in a valve 82, thus causing the table or carriage 40a to start outwardly carrying the grinding wheel 37 past a stationary dressing device 83, Fig. 3. However, the fluid does not immediatelv'flow through the pipe 80 to cause the table 40 tojimmediately move outwardly in similar fashion because of the interposition of a valve 84 in the said pipins: 80. whose single valve passage 85 is at this time so disposed as to preve t the passage of any fluid therethrough. 'Ifl'hen, how ever, the table 40a has moved through a predetermined portion of its outward travel,

a cam 'member'; 86 adjustably attached; to

said table 40a as shown in Fig. 5, engages a pump of the usual sort provided .entrance and exit ports tached to a member 98 that thus turning the pin 87 carried by an 88, thusrocking I 1/ tion places the passage 85 in line with the of the valve casing, thus allowing the pressure fluid td flow into the left hand end of the cylinder 74, the fluid flogvidng through a port or passage 90 pro- W e provide for the return of the. arm 88"and consequently the valve member 84 to its initial position.

in a valve member 91, the purpose of which will hereinafter appear. In order to and in order to providefor adjustment thereof, a screw'92 is provided,

located in a block 93 attached to the base 43a, as shown-in Fig. 5.

The foregoing action starts the' table 40 controlled by the fluid pressure cylinder 74 to move to the right, the grinding wheels 37,

vices 83 and 83a respectively, which are fas- .t'ened to some stationary portion of the reoutwardly, andthe tables 40 and 40a continue 3 spective bases 43 and 43a. The reversals of "the saidtables to carry them back to their initial position subsequent to the first passage of the wheels past said dressing device is under the control of the table 40 '(which Wasthe table that started its outward movementlast. as just described) and this is effected in the following manner A pair of stops or dogs 94 and 95 are attached to the table 40; in the'path of the dog 94 is a roller 96','while in the 95 is a roller 97, these rollers being both atis in turn fas-. tened to a shaft 99 fastened to or integrally formed with the valve member 82.

When, in the outward travel of the table or carriage 40, the dog 94 comes in contact with the roller 96, the member 98 is rocked, shaft 99, and with it the. valve member 82. This turns the passa 81 angularlv. passage of fluidthrough the piping 80a, and therefore stops-the movement of the table .4021; at the sametime a passage 100 in the aforesaid valve member 82 is mo ved so as to piping 101, which causes the pressure fluid to flow into said piping 101. The piping 101 communicates through aport 102 with the ,in-

terior of a cylinder 103 in which is-a piston the piston'104 120 path of the dog and thus prevents the further place in communication the piping 80a and coil spring not shown, which has been heretofore mentioned, immediately causes the ratchet wheel '55 to spring back to its initial position, where it is held by adjustable stops not necessary to be described herein. This action moves the cam portion 61 from the roller 62, and thus causes the valve member Likewise, the passage 100 still connecting the piping 80a and 101, and the piping 79 being connected to an exhaust port 106, the fluid is forced out of the cylinder 103 by the action of the spring 60 reacting on the hold pawl 58. The table 40a, however, does not move, the fluid being locked in the cylinder 74a by reason of the fact that a solid portion of the valve member 82 is interposed between the piping 80a and 80b.

' The table 40 continues its return motion, and ultimately the dog 95 contacts with the roller 97, and this rocks the member 98 in a counterclockwise direction, revolving the shaft 99 and placing the valve member 82 in its initial position, as shown in Fig. 6. Fluid being now allowed to pass from the left hand end of the cylinder 74athrough the piping 80b, passage 81, piping 80a, and 79, into the exhaust port 106, the pressure fluid, which is active through the pipings 72 and 73a moves the piston in the cylinder 7 4a to the left, thus starting the table or carriage 40a on its return motion, carrying the grinding wheel 37a a second time past the dressing device 83a. Both tables thus return to their original position where they are held by the engagement of the movable stops 77 and 7 7a with the stationary stops 76 and 76a.

It has been found desirable to cushion the return stroke of the table 40 as well as the outward stroke just prior to the reversal thereof. This could be done as shown in the copending application referredto, in which case both tables were cushioned on their return strokes; as herein shown only the table 40 is cushioned owing to the fact that it is not so important to keep the table 4.00, from rebounding since it is given a separate feed into the work in a line perpendicular to its axis,

' as described in the aforesaid Heald et al. pate'nt, which causes the contact of the grinding wheel 37a with the workpiece, where as in the case of the grinding wheel 37, rebound of the table carrymg it must be prevented or the flange C would be destroyed.

Referring now to Fig. 4, a pair of cam blocks 107 and 108 are adjustably secured to the table 40. These cam blocks provide inclined cam surfaces 109and 110 respectively;

at the commencement of movement of the table or carriage 40 to carry the grinding wheel past the dressing device, surface 1 10 is in contact with a roller 111 provided by an arm 112, that is urged in a counterclockwise direction to hold said roller against said cam surface, as by means of a coil spring 113, an adjust able stop 114, adapted to engage a projecting portion 115, being provided to prevent the movement of the roller 111 upward'beyond a certain desired point. The arm 112 is connected by means of a link 116 to an arm 117 which is fastened to a shaft 118 fastened to the valve member 91. At the start of the movement of the table 42 to cause the grinding wheel 37 to be dressed and trued, the passage 90 in the valve member 91 bears such an angular relation to the entrance and exit ports. of the pipe 80, that the fluid is considerably impeded in its flow therethrough. Consequently the table starts to travel at a throttled speed, but as it moves, the cam surface 110 gradually allows the roller 111 to rise, and this finally places the passage 90 in the position shown in Fig. 6, which corresponds to the position of parts shown in Fig.

4. After a short travel of the table 40 at its unthrottled speed, the roller engages the cam surface 109, and the cam block 108 is so set action takes place with the table traveling at a reduced speed. This is desirable as it prevents over run of the table 40 and thus increases the accuracy of functioning of the whole machine. It will be remembered that in the case of the table 40a that it is stopped altogether by the turning of the member 98 and no such means of cushioning its outward stroke is necessary.

On the return motion of the table 40 it will be readily seen that the table first travels slowly, and then at a higher speed, and ultimately is reduced in speed again by engagement of the cam surface 109 with the roller 111. This causes the table to be cushioned before the stop 77 strikes the stop 76 and thls prevents the rebound of the table. It should be noted that the fact that the table 40 is brought to a stop slowly while the table @Oa is stopped without any cushioning device, serves to synchronize the movement of the tables to cause them to complete this movement at the same time, the table or carriage 40a being the last to start on its return movement.

When the grinding wheels have been dressed and trued once, it is obvious that subsequent withdrawal motions of the tables will not cause any of the material of the wheels to be removed, unless some means is provided to cause the dressing devices and the wheels to approach each other. The machine of the present invention provides automatic means to compensate for wear and previous dressing of the grinding wheels, so that each dressing operation may remove some material from the wheels, and the latter be thereby kept to the exact required size in order to produce uniformly groun workand 43a provide adjustable-brackets 119'and pieces. As sh vn in Figs. land 5, bases 43 119a upon which are mounted cams 120 and 120a respectively. Tables '40 and 40a provide pivotally mounted arms 121 and 121a, providing rollers 122 and 122a that are adapted to engage the cams and ride thereon, when the tables start to move to the right. The arms 121 and 121a carry pawls 123 and 123a that are'spring pressed outwardly. Uponmovement of the "arms as above described, the pawls engage adjustable inclined surfaces 124 and 124a provided by pivotally mounted members '125 and 125a that are held in an adjustable' position in "any suitable manner. Said pawls are thus directed inwardly toward ratchet wheels 126 and-126a and thus move saidratchet wheels through-the dis- 37a have entirely disappeared tance of one or 'more teeth, depending upon, the setting of the members 125 and 125a. As

the ratchet wheels are connected, directly or' tention at all once the work-loading hopper has been filled, (said work-loading hopper being ishoW n in the copending application S. No. 359,617 of Quimby referred to), and besides the danger of dressing the wheels entirely away, as aforesaid, it is desirable that the wheels should be changed before they have become too small, as gr' ding elficiency is greatly impaired, and there is danger of spoiling the workpiece and .-the wheel spindle, by re-' duction of the wheels to too small a diameter. Even in a manually loaded machine, which is all that the present application discloses since the work-loading mechanism forms no part of this invention, it is desirable to warn the operator in some manner that the wheels have i been reduced below the eflicient cutting diamelectromagnet '1-27. Electromagnet 127 is lead 128 from the eter. '11: these ends, mechanism'for s motor 11 when either wheel 37 an 37 a reaches pping the rotation of the the minlmum allowable diameter.

Referring now to Fig. 7, the switch 27 which connects the power main 26 to the conductor 28 leading to one armature brush of the motor. 11, is kept closedby meansof au energized through the following circuit A power main 25 runs to said magnet 127; the other terminal of said magnet is connected to a lead 129that connects to invention is -re-:

the machine provides. a

Q i a switch 130 the purpose of which will be presently explained. Another lead 131 from said switch carries the said current through a switch ,132 and then,.by a lead 133 to a switch 134, by a lead 135 to a switch 136, and bya lead'137 to the power line 26. It will be apparent that if either switch 134 or 136 is opened, the magnet 127 will be deenergized, and therefore the switch 27 opened, which will stop the motor 11.

. Means is provided to open the switch 134 or Q 136 upon the movement of the cross slide 39 or 39a beyond a desired position. To that end, a bracket 138 is secured to an'da bracket 139 is se ured to the turret 44, and these brat kets hold 136 respectively. ,Adjustable screws 140 and 141 carried by the cross slides 39 and 39a respectively, these screws'being located in bosses 142 and143 respectively, fastened 'to said cross slides. When. in the successive advancement of a. cross slide it moves so far that 1 its adjustable screw 140 or 141 contacts with button portions 144 or 145 respectively pro vided by the switches 134 or 136, one or the other of said switches is opened, and as they are in series this deenergizes the magnet 127, opens the switch 27, and stops the motor 11.

As heretofore stated, one -01? the main objects of'thepresent invention is to so control the movement of the mechanically operated elements that there 'will be nopossibility of their continuing to functionin case the by draulically operatedelements failto come to their proper position. As embodied in the present machine, this involves the stoppage of the electric motor that raises and lowers the table 40,

} so the switches 134 and" the work slide 3 upon movement of the tables 140 and 40a as just described. However, in the interest of obtaining the maximum-productiori, it is desirable that the motor 11 be not stopped until the work carrying slide 3 is practically ready to descend; in other words, at thattime when the long dwell on the cam 22 is just about ready to leave the roller 24. To that'end, I have provided a pair of electric circuits, the maintenance of,

one of which is necessary to the continued energization of the motor 11; when the table 40a first starts outwardly (the movement of this table,. as heretoforeexplained being a condition precedent to the movement of the table 40) it breaks one of these electric circuits while the rotation of the-cam 22 breaks the other. i

As shown in Figs. carried by the table 40a is incorporated in a block 77 b, which may be held in any desired position by means of an, adjustment screw 146 projecting from a block 146a, this ex- 1, 5, and 7, the stop 77d pedient being adopted chieflyto facilitate ac-' curate adjustment of the bloclf'flb.v A de pendingarm 147 carried by the block 776 carries an adjustable 'screw 148 that is normally in contact with a push button 149 of a switch device 150. When the table 40a starts on its outward travel the screw 148 leaves the push 1 button 149, and this breaks the circuit through the switch 150 and opens the circuit through 5 leads 151 and 152, which are shunted across the leads 129 and 131 and constitute an alternate path of travel for the current from the mains 25 and 26 to the magnet 127, the path leading through the leads 129 and 131 having already previously been described.

Since the current may still flow through leads 129 and 131 to energize the magnet 127 and thus to keep closed the switch 27 in the circuit leading to the motor 11, the said motor does not immediately stop, but con-- tinues to revolve until such time as, in the 153 attached thereto, engages a roller 154 provided by an arm 155pivotally mounted at 156 to the machine frame. The arm 155 carries an adjustment screw 157, which is in engagement with a button 158 of the switch 130, already mentioned. When the cam portion 153 engages the roller 154, the button 158 is pushed inwardly, and this breaks the circuit through the switch 130 that connects the leads 129 and 131, as already explained. This shuts off the only remaining path for the current to the switch 27, and thus deenergizes the magnet 127, and as the switch 27 immediately opens, the motor 11 stops.

With the current to the motor 11 cut off, the cam 22 stops revolving, and indeed all mechanically actuated parts of the machine cease moving. As the motor 66, however, still w rotates, the pump 65 continues to function and the tables or carriages and 40a move through the dressing cycle as-already described. It will be remembered that the 40 table or carriage 400. was thefirst to startoutwardly and the last to return. Consequently there can be no movement of the table 40 till the machine has been put in such a condition that the work carrying slide 3 r can not possibly descend, and as the movement of the table 40a opens the switch 150 and therefore ultimately the switch 27, there can be no interference between the fluid pressure operated slide 40a and the mechanically operated slide 3, or any mechanism or parts carried by either of them. And insomuch as Y the slide 40a is the last to return to its original position, both slides or carriages will be in a position of absolute rest when the circuit is remade through the switch 150, by

.the contact of the screw 148 with the button 149.

At this juncture the slide 40, which returned first and was cushioned in its move ment has been brought to a stand still, and the slide 40a is about to stop or has stopped. With the remaking of the contact at 150, and the consequent establishment. of the circuit through electromagnet127, from power main. 5 25, lead 128, through said magnet and by to their positions of rest. revolution of the cam 22, a small cam piece I the machine frame.

way of leads 129, 151, switch 150, leads 152,

131, switch 132, lead 133, switch 134, lead 135, switch 136, and lead 137 to the power main 26; the switch 27 is closed, and the motor 11 immediately starts to function and the slide 3, without any lost time, to descend, because the ,dwell on the cam 22 is about to' leave the roller 24. It will thus be seen that the machine is completely safeguarded from breakages due to malfunctioning or misflmctioning of any of'its parts-ormotions and at the same time there is no unnecessary dc;

lay in the operatipn thereof, the mechanically moved parts resuming their motion immediately upon the restoration of the carriages As heretofore explained, themachine desirably provides automatic means to stop the rotation of the work spindle 5 and automatic means for actuating the expansible collet 6.

As already described, the work carrying spindle 5 is rotated from a pulley 7, which is rotatably mounted on a stationary part of Said pulley 7 is driven from the motor 11 in the following manner:As will be recollected the pulley 12 on the motor shaft drives a pulley 14 by means of a belt 13. Upon the shaft 15 to which said pulley 14 is fastened is keyed another pulley 159 and the latter, by means of a belt 160, drives a pulley 161 fastened to a shaft 162 upon which the pulley 7 is mounted. The pulley 7 is free uponthe shaft 162 but,-by means of a friction clutch, the inner cone of which is keyed to said shaft 162, the pulley 7 is normally'caused to rotate with, the shaft. The means for holding the inner cone against the outer cone that is integral with the pulley 7, is a spring not shown herein, the details of this clutch mechanism beingfully illustrated in the aforesaid Heald et al. patent; 'suflice it to note in the present machine that a cam-member 163 fastened to the work carrying slide 3, engages, when said slide has moved to its upper position, a roller 164 carried by a lever 165, and through the medium of a link 166 causes 'a lever-.167 to shift the clutch, a bifurcated, member 168 engaging a collar 169 on one of the clutch parts serving to move it to disengaged position. In this manner the rotation of the spindle is automatically stopped when the .slide 3 arrives at its upper position as shown 2 .taken in connection with Fig. 6, piping 170 is shunted into the main supply pipe. 67 leading from the pump 65. This piping leads to 1 a valve 171, the location of which on the machine .is best shown in chine, to an exhaust Fig. 2. The valve member 172 of valve there. is a piston 177. So leng as the cylinder 176 is connected to the exhaust, as

already described, the actuating rod 6a for the expanding" collet 6 remains in its rearward position, the collet being kept in its expanded position to hold a workpiece by springs not bar 179 carried thereby engages a valve memberin the port-173 to c z I at 186 to the machineframe.

rearward position by shown, and rod 6a being maintained in. its means of aspring 178. the slide 3-rises, a lug, or roller 180, thus urging an'arm 181 in a clockwise direction against" the tension of a coilspring 182. The arm 181 is fastened to asha-ft not, shown, which is integral with the valve member 172,and' thus partial rotation of this en, however,

onnect the iping 170 tothe piping 174.. This. makes the premure active'in the cylinder 176, and thus forces the piston 177 to the right, Fig. 1, urging the pin 184 against a lever 185 p h The lever 185is a bell .crank lever pivoted The other end of said lever is attached as by means of a link 187 to a lever 188 pivoted at 189. vThe upper end of the lever 188 includes .a bifurcated'portion which presses against adjustable nuts 190 on a screw-threaded portion of the shaft 6a; when, as aforesaid, the piston 177 is moved, the pin 184 rocks'the bell crank lever 185 in a clockwise direction, and this and movesthe ro -40 disconnects the forces the lever 188 in the same direction, d 6a forwardly. The movement is a; very powerful one, because the left hand end of the bell crank lever 185 together with the link 187 constitutes a toggle ing thus moved forwardly to unclutch the workholding devicefi, it is so maintained until,

in the subsequent downward movement of the slide 3, the lug 179 leaves the roller 180, which allows the valve member 172, under the influence of the spring initial position as shown in Fig. 6, and this cylinder 176 from, the source of fluid pressure and connects it instead to the exhaust pipe 175: the'parts are .thus restored to their original position under the influence of thespring 178, and the collet 6 is expanded? been indicated in the foregoing detailed description of the various parts and separate mechanisms thereofto will nevertheless be briefly recapitulated. Having adjustedthe dressing diamonds 83 and 83a or the holding. devices therefor, which may be of any suitable type. and having properly adjusted the cross-slides39-and duced as just set forth, turns f 182, to resumedts 37 39a, asby' means 191 and 191a, the in motion, ing set the usual hand wheels operator sets the machine as by closing the switch 132. Havmechanismin the counting box 45 so that the tables or carriages 40 and 40;: will very presently undergo movements to dress and their reciprocatory true the grinding wheels 37 and 37a, which setting of the counting the mann mechamsm-may er set forth in the aforesaid Heald et' al. patent, the operator readily be done in allows the machine to go through-one cycleof operation in order to insure the loca grinding wheels'37. and 37 a in th tion of peripheries of the e proper respective vertical planes. The dressing operation having mechanism ing in the fut desired dete wor will once ure t rmin may be reset soas'to ate number of kpieces .have been ground; the then set in'operation the automatic means or placing workpieces on'the expanding coloccured, the counting box causedress- 0 take place only after theseparate operator let 6, in case such mechanism is employed, or,

if the machine is in this respect he has risen,

rotation at a redu to be manually operated wilil wait until the slide 3 the spindle 5 come to'a stop and said collet 6 contracted.

- The operator will then upon the collet 6; the ca place a workpiece a m 22 continue its ced rate of speed, so long as the slide 3 is up, because the circuit front the power mains 25 and 26- through the shunt leads 31 and '32 h as been broken, by reason of the actuation of the switch 33, thus compelling the electrical the field coils 1 the rheostat 30. outer dwell of the thus allowing the 92 of the motor 11 energy to flow by way of Ultimately, however, the cam 22 leaves the roller 24- slide 3 to commence its descent, and this action draws the adjustment screw away from the switch 33, allowing said switchto close, and

short circuiting the rheo-J stat 30. The motor 11 immediately picks up speed, and

of the mach workpiece wheels 37 and 37a,

Wheel 37 the mechanically ine move at higher velocity. The a now conta actuated parts cts with the grinding the conical surface of sai workpiece approaching said grinding wheel in a tangential path,vand the grinding a subsequently'moving into con- H5 tact with the undersi forth in the afores The grinding wheel de of the flange b as set aid Heald et al. patent. s 37 and 37a are held in positions indicated in Fig. 3 in a longitudinal direction by means the cylinders 74 and Although the operation. of the machine has being urged again of the fluidpresure in 74a, the stops 77 and 770 st the stops 76' and 76a,

and the tables 40 and 40a carrying said grindduring the locatio tom position (the radius of the cam ing wheels being thus held a certain extent. it The grinding operation thus. takes stationary."

place of the slide 3 at its botdwell portion of small 22 may be slightly invoto cause a gradual action) c said slide is carried upthrough 100' A ward again, the grinding wheel 37a first moving away from the flange b so that the workpiece a may move upwardly without said ange being destroyed. When the adjustment screw contacts the button of the switch 33, the motor 11 is again slowed down by reason of the incorporation'of the rheostat 30 into the circuit through the field coil-.192.

The grindin of individual workpieces thus continues, eac revolution of the cam shaft 21, signifying a separate grinding operation, causing movement of the'pawl 54, said pawl being moved substantially as the slide reaches the top of its stroke each time, until ultimately, after a determinate plurality of grinding operations, the cam member 61 moves the roller 62 to the right, thus raising the valve member 7 O, and causing the table or carriage 40a to move outwardly. This action, as already described, moves the adjustable screw 148 away from the contact button 149, and opens the switch 150.. When, by reason of the operation of the arm 88 by the cam 86, the valve 84 is turned, the carriage 40 also moves outwardly. This ultimately causes resetting of the ratchet wheel 55 in the counting box, and return of the carriage 40, the reversal thereof occuring by reason of the contact of the dog 94 with the roller 96. As the slide 40 returns to its position of rest, the dog 95 contacts with the roller 97,

and this turns the valve 82, and starts the carriage 40a on its return stroke. By this time the mechanical movements of the machine will probably have stopped, sincethe .cam piece 153 on' the cam 22 will have opened the alternate circuit through the leads 129 and 131, thus. deenergizing the magnet 127 and opening the switch 27. At least it will be seen that the cam 22 can not possibly move beyond the point where the cam piece 153 contacts with the roller 154, and so the slide 3 is absolutely prevented from moving downwardly until such time as the carriages 40 and 40a have resumed their initial position, the last carriage to return, viz. 40a, being the one that makes the circuit at 150, thus completing one of the alternate paths of travel for the current that energizes magnet 127. Said magnet being thus reenergized, the switch 27 is closed, and the motor 11 starts up again. It should be noted that the automatic starting of the motor 11 takes place when the current through the field coils 192 is forced to go through the rheostat 30,"and thus over loading of said motor 11 is prevented.

The machine now resumes its normal operation, going through the simple cycle first escribed in this description of operation, until such time as the cam member 61 again makes contact with the roller 62, whereupon the dressing cycle, to dress and true the grinding wheels 37 and 37a, is repeated. The dressing of the grinding wheels occurs repeatedly at the predetermined times until one or both of said wheels are reduced to a predetermined limit of size, at which time either one or both of the switches 134 and 136 are opened, thereby causing the main motor 11 to stop, due to the opening of the switch 27 in the power line 26.

-From the foregoing description of operation it will be apparent that the machine presents two sets of mechanisms, one actuated .controlled and operated through the mechanical train of mechanism, shifts the control of the machine to the fluid pressure mechanism, and stops the mechanical movements,

whereupon the fluid pressure operating mechanism continues its function, it alone then being the live element of the machine, and

when the fluid pressure mechanism has completed its work, the coordinating electrical apparatus reshifts the control of the machine to the mechanically operated mechanism, the fluid pressure operating mechanism remaining in a passive state throughout the remainder of a single cycle of full operation of the machine.

It will be further apparent that the hydraulically operated-mechanism of the machine is herein shown as embodied in two separate parts, which move separately but.

are controlled through a single fluid pressure system, the movement of one being a condition precedent to the movement of the other, and the reversal in direction of travel of the first being effected by movement of the second, so that neither may operate independently of the other and both will move in COOI'Cllnated sequence. It, will be further apparent that the hydraulically operated mechanism first to move and last to return is the element which takes control of the machine and ultimately restores control to the mechanically operated train. It will also be apparent that the machine will continue to go through its regular cycles. of operation until one or the other of the grinding wheels becomes worn down to a predetermined limit of size; thereupon the machine is automatically brought to rest for the replacement of the worn. out wheel or-wheels. .These several features'of the invention present many advantages in that the separate operations of the machine can take place without danger to itself or to the operator thereof, and this, stated generally, is the crux of the present invention.

I claim,

1. In apparatus'of the class described,-a pair of-tables or carriages, individual fluid pressure means to operate said carriages,

means for setting in operation the fluld means actuated by said second carriage to reverse it'sown movement.

2?. In apparatus ofstheclass described, a

pair of tables or carriages, individual fluid. pressure means to operate said carriages, meansfor setting in operation the fluid pressure to procure movement of one of said carriages', means responsive to movement of said first carriage-for setting in operation the fluid pressure to move the other carriage,'means responsive to movement of the second carriage to reverse the direction of movement of said second carriage, and means responsive to re verse movement of the second carriage for thereafter reversing the direction of travel of r the fist carriage.

4. In apparatus of the class described, a

pair oftables or carriages,-individual fluidpressure means to operate said carriages,

means for setting in operation the fluid presfr sure to procure movement of one of said barriages, mechanically actuated elements in 7 said apparatus, means responsive to movement -of said first carriage to prevent the movement of said mechanically actuated elements of the apparatus beyond I a cer tain desired point, other means respon sive to movement of said first carriage for setting in operation the fluid pressure to procure ,movement of the other carriage, means responsive to movement of the second carriage to reverse its own movement, means responsive to the reverse movement of the second carriage for thereafter reve the direction of travel of the first carriage, and means responsive to reverse movement of one 0 said carriages for thereafter settin parts of the apparatus.

5. In a grinding machine, a carriage or slide, mechanical means to reciprocate said carriage or slide, a table or carriage, fluid pressure means to move said table or carriage, means set in operation after one or more reciprocations. of the slide for causing movement of the table, means operated by the movement of the table for setting a guard to prevent movement of the slide beyond a defito, a switch insaidmains,

nite position,and means operated by retui'n of the table .or carriage guard.

6. In a a slide, means to reciprocateit, a table'or car riage, means to move it, means set in opera tion after one or morereciprocations of the slide for causing movement of the table, means operated by the movement of the table for setting a guard to prevent movement of r removing the the slide beyond a definite position, and means grinding machine, a carriage or operated by return of thtable' or carriagefor removing the guard.

7 In a grinding machme, a carriage or slide, a revoluble cam to move said carnage or slide, an electric. motor to revolve thecam,

and means down when movement.

8. In a grinding machine, a carriageor to cause said motor to be slowed said slide is near one end of its slide, a revoluble cam to move said carriage or slide, an electric motor to revolve the cam, a

rheosta-t, and means for placing the rheostat' in circuit with one or more said motor to slow down the same when the slide is near one end of its movement.

- 9.'In a grinding machine, a grinding wheel, a motor driving a slide adapted to move the work in relation to. said grinding wheel, power mains conveying current thereelectro-magnetic means for keeping said switch closed, a pair of alternate circuits for energizing said electro-magnetic means, a table or carriage movement of whichbreaks one of said circuits, and a mechanical element deriving movement om the said electric motor which at a certain predetermined of said circuits.

10. In a grinding machine, agrinding wheel, automatic means for periodically dressing said grinding wheel, and automatic means to prevent further operation of the machine when the said grinding wheel has been reduced to a definite minimum diameter.

11, In a grinding machine, a grinding automatic means for; periodically dressmg said grinding wheel, and means to stop the machine when the said grinding wheel has been reduced to a definite minimum diameter. a

12. In 'agrinding machine, a grinding wheel, a wheel operation of the machine for causing said grinding wheel to move relative to the dressing device to dress and true the wheel, further means actuated automatically for causing relative movement between said wheel and dressing device in a line transverse to the aforesaid movement to insule successive dressing operations, and means operated by said last named means for stopping the machine upon the reduction of the wheel to a certain minimum diameter.

ofthe coils of the position breaks the other a dressing device, means acg tuated automatically and periodically in the in operation ag'amthe mechanically actuated 13. Ina grinding machine, a grinding wheel, a wheel dressing device, means actuated automatically and periodically in the wheel, an expansible collet to hold a workpiece, means to cause said grinding wheel and said collet to approach and recede one relative to theother, the relative motion being. at an angle to the axis of the collet, and automatic means for placing said collet in condition to receive a workpiece upon sepa ration of said collet and the grinding wheel.

15. In a grinding machine, a grinding wheel, an expansible collet to hold a workpiece, fluid pressure means to open and close said collet to place itin condition to receive a workpiece or to hold it for grinding, means to cause said grinding wheel aifd said collet to approach and recede one relative to theother,- the relative motion being at an angle to the axis of the collet, and automatic means for causing actuation of said fluid pressure means upon separation of. said collet and the grinding wheel.

16. In a grinding machine, a grinding Wheel, an expansible collet to hold a workpiece, fluid pressure means to open and close said collet to place it in condition to receive aAvorkpiece or to hold it for grinding, means to cause said grinding wheel and said collet to approach and recede one relative to the other, the relative motionbeing at anangle to the axis of the collet, and means operated by said last named means for causing periodic actuation of said fluid pressure means.

17. In a grinding machine, a grinding wheel, work holding means, a wheel dressing device, means to cause relative movement between said workholding means and said grindin wheel in the normal operation'of the mac ine whereby to grind a workpiece. means to periodically cause a relative movement between the grinding wheel and wheel dressing device to dress and true the wheel, and means to prevent approach between the grinding wheel and the .workholding means while the wheel is being dressed. 18. An automatic grinderhaving a grinding Wheel in combination with a shut-down device operative when the'wheel wears away to any predetermined limit of size.

19. In a grindlng machine, a grinding wheel, a dressing -"device therefor, means for producing successive relative approaching 14.-In a grinding machine, agrinding movements between said wheel and said device, and a shutdown device for the machine, 7

carria e. e A Gazette February 5, 193i] DISCLAIMER 1,901,236. -Waldo J. Guild, Worcester; Mass. GRINIDI-NG MACHINE. :Pate nt dated March 14, 1933-. Disclaimrifiled December 31, 1934, by the assignee, .The i l Heald'Machine Company.

Herebyenters this disclaimer to claim -1 insaid specification which is in the {01- I lowing words, to Wit: r

. 1. In apparatus of the class described, a pair of tables or carriages, indiridual fluid pressure means to operate said carriages, means for setting in operation the fluid pressure to procure'movement of one of said carriages, and means responslve to movement of sald first carriage for settmg'the fluid pressure in operation to move the other

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