US2162038A - Grinding machine - Google Patents

Description

June 13, 1939.

:w. TRI BLE I GRINDING MACHINE Filed May 17, 1937 2 Sheets-Sheet l INVENT OR.

ATTORNEY.

June 13, 1939. TR ;v 2,162,038

GRINDING MACHINE I Filed May 17, 1937 2 Sheets-Sheet 2 l l I 59 inn 1mm;

ATTORNEY.

Patented June 13, 1939' A UNITED STATES ;PATENT- OFFICE I GRINDING mcnmn Winthrop a, Cincinnati, Ohio, assignorto Cincinnati Grinders Incorporated, Cincinnati, Ohio, a corporation of Ohio Application May 17,1931,- Serial No. 143.055 12 Claims. (01. 51-166 This invention relates to improvements in. grinding machines, and has particular reference to a novel and improvedmechanism for determining the surface-speed or rate of rotationof it; a grinding wheel.

According to present commercial practices, in precision grinding and particularly in continuous production work, such as motor vehicle plants or the like, it is desirable to reduce to a mini-.

10 mum the shut-down time necessitated for removal and replacement of the wearing part of the machine, namely, the grinding, wheel. Ma-

chinesare, therefore, designed to utilize a wheel having a large. initial diameter which-may be greatly reduced in size before replacement is necessary;

It is, however, a recognized fact that such grinding wheels are normally designed and constructed for operation within a certain maxi:

. mum surface speed as distinguished from the safe R. P. M., the R. P. M. necessary for efli- .cient grinding, therefore, increasinginversely as the diameter of the grinding wheel decreases. For most eflici'ent operation, it is, therefore, de- 5 sirab that the speed of the wheel increases as i periphery decreases so that the surface v speed shall remain as nearly as practicable a constant during the useful life of the wheel. 30 At the-same time, it is essential, both for; safety to the operator and; for attainment of best grinding results, thatmeans'be provided, preventing -initial operation in excess of a prescribed pre -c selected 'speedordinarily in the nature of 6500 35 feet per. minute.

- It is, therefore, one of the purposes of the pres- .ent invention to provide a controlmechanism for the'w h'eel operation whichfas distinguished from prior art mechanisms having reference to 40 independent adjustment of their mechanical ele-' 'men't's, is dependent on an adjustment, f a

member directly related to the wheel 1 and- "whose position is affunction of thesizeof the wheel .for, automatically controlling the speed at which said wheel iaoperated. h

4 'A' further object of the invention is the provision, inconnection with a wheel diamete fdetermining of a coupled, automatic control device for varying .rate of 'operation of the wheel in accordance with the actual additional object of the present-invention ,is of a'mecbanism which maybe -readily appliedto of grinding ma-- I itmwheel.

- cured on the carriage l .and includes a .transspeed thereof in accordance of my invention. I An additional object of the present invention is the provision of a mechanism which shall be automatically. effective for determination of the maximum potential surface speed of the wheel while permitting selective operation, as desired,

at lesser speeds than said automatically determined maximumI Other objects and advantages of the-present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings forming a part thereof and it is to be understood that any modifications may be made in the spewith the principles 'cific structural details there shown and hereinafter described, within the-scope of the appended claims, without ,departing from or exceeding the spirit of the invention. I In the drawings in which certain specific em- -bodiments of the invention have been illustrated:

Figure 1 is a fragmentary'side elevation of a portion of a grinding machine equipped with my improvements. v

. ,Figure 2 is a fragmentary. plan view of the earn carrying bracket.

, Figure 3.is an enlarged pan view partially in section as on the line 33.of Figure 1. Figure 4 is an electrical diagram illustrating the principles 'of the present invention. 0

, 3 Figure 5 is a fragmentary sectional view illustrating a continuously adjustable form of rheostat device; and Figure 6 isa corresponding fragmentary elvational view thereof.

Figure 6 is an and elevation ofthe rack and wheel i5 is a wheel guard it having a slot 2! for reception of the inner end of a wheel truing mechanism. '7

This mechanism, as particularly illustrated in- Figures 1 and 3, is carried by a bracket 2| se--' 7 versely sbiftable, slide 22 actuated as by the piston" cylinder mechanism 23 for traversing the diamond or like truing device 24 across the periphery of the wheel. diamond 24 is carried by a rod. 4

' a,1ea,osa

or plunger 2| slida'bly adjusted in sleeve is, as as at is cooperating with rollers u on the switch by screw 21 rotatably or non-translatably mount-' ,ed in cap 28 on the outer endof sleeve 26 in which the rod Ilis'slidably keyed. An actuating 5 handle 3. serves to rotate the screw and thus to effect a limited in and .out movement of the "truing member 24. The sleeve 28 is, in turn, slidably engaged in clamp bearings of profiling slide 82,, translatable with and with respect The fore oing parts are of themselves well "known-to the art, and it is believed-do not require further detailed description.

ReferringtoFlgure4,itistobenotedthat 15 the motor ll includes the rotating armature as having coupled thereto the power lines 3H5 through the control. including a conventional armature accelerating contactor and resistor.

The field ls shunt wound, as indicated at 3], and- 1 a comprises in the field circuit the leads II and 3!.

Interposed between these leads is the variable resistance speed control rheostat 4| having the operating handle H by which the resistance may be increased to reduce the field strength and thus 88 effect desired speeding up of the motor.

so ble'type as indicated'at u in Figure 5.

, m the case of the form of the invention illustrated in Figure 4, the circuit, as an entirety, when the machine is supplied with a new full diameter grinding wheel, is normally closed I through the switch plates 44 and (I connected in parallel with-resistances-ll' and 42 respectively, therefore rendering these resistances inefiective. with the circuit thus conditioned, it will be understood maximum effect .exists in the shunt slower speed, the exact rate being dependent upon the adjustment of the manual rate controller 4| for variably determining the -motor,-

and thus thegrinding wheel speed.

It is, of course, to be understood that the efi'ective peripheral surface of the grinding-wheel II is initlally'formed and subsequently recondi-' tioned by traversing thereof by the truing device 2 and that it is necessary when a new wheel 50 is to be'mounted in themachine that the truing V device be retracted to' a position whereit will clear the maximum initial diameter of the wheel.

Itwill further be understood that as the diam-;

eter of the grinding wheel decreases, due either 55 to wear from operation or necessity of reconditioning of the surface to secure best grinding conditions, that'the truing device 24 follows up .e'xactly-and accurately lthe wheel radius and at all times serves as an accurate. to gage device, indicating exteriorly of the guard thesize of wheel then existingwithin the guard. Also, since the reduction of the wheel is efiected "by the truing device and itssetting there exists no variance or lost motion between the parts,

as and no backing oi! or like'adjustment is n ecesji sary. Consequently, this combined gaging and size determining member forthe grinding wheel affords an ideal device for utilization in 'autoshown, as attached to the-cap member 28, the

bracket or support plate having'rremov'ably 1 and adjustably secured thereto, as by the screws n, 41, the cam bars-ll tracks arms for respectively controlling the opening and-closing of the switches orcontacts It and L It will be noted, particularly by reference to Figure 1, that when the truing device is in its outwardly retracted position the two cam bars serve to maintain the members 44 and ll in circuit closing position so that the motor can be operated only at its slower rates of speed. On the other hand, as the truing tool moves inward during reduction of the grinding wheel diameter,

first, one, and then theother, of the bars I! will release the respective rollers ill, causing successive movements of the members 46 and 44 into openposition so that, first, resistance 42, and subsequently resistance M, is thrown into the shunt field of the motor, causing successive'potential increases in motor speed which can, of course, be-to an extent counteracted by manual adjustment ofthe variable resistance l0. It is, of course, to beunderstood that the inward adjustment of the truing tool may 'be effected as to minute variations for individual surface reconditionings through handle II and screw 21, while -general' longitudinal adjustment of sleeve 26 may be produced in any desired manner as, for example, by slight loosening of the clamps '3land employment of a progressive adlusting device, such as the hand wheel I! 'opera'ting a pinion engaged with rack II on the sleeve. It is further to be understoodthat while 7 but two cam members have been illustrated, that the number of these may be varied as desired "with corresponding individual resistances controlled thereby; also, that the relative positioning of the cam grooves with their stepoifs may be varied by relative longitudinal adjustment of the members ll with respect to their supporting bracket .40, and in this manner the fiel oithe m r wh h wi n operate at its particular point at which a speed variation is automatically effected may be accurately selected.

Additionally, as has been. indicated in connection with Figures 5 and. 6, in place'of, or in addition to, employment of the cam bars ll, use may be made of a rack bar, such as It, engageable with the gear 55 on pinion shaft I. which, in turn. bears pinion ll meshing with the periphery of gear 58 having contact member ll 1 for cooperation with the contacts ll of the .rheostat 43. In this form of the invention,'the' number of resistances "-42 arethereby greatly multiplied over the single'paii' indicated in the diagrammatic view Figure 4, with the result that a finer, controlof wheel speed may be effected-still depending directly on the wheel radius ordiameter as continuously accurately .iustmentl a In present day grinding operationawhile, as before mentioned, it is ordinarily desired that the R. P. M. of the grinding wheel spindle be increased as the wheel diameter is decreased 7 this, or course, is effective only to maintain a substantially constant-surface speed and therefore constant cutting action as respects the measured and determined by the truing tool adv grinding wheel. .In some instances, however, it v is desirable .that the wheel be operated at a].

slower speed for special finishing operations.- In.

order that this may be: readily accomplished}! preferably provide, in parallel with the series of resistances such' as "-42 and their 'control plates,- a second circuit 6i controlled by the speed control selector switch 61. In other' words, when this switch is closed, the auxiliary resist 'ances become ineffective and the motor, and thus I.

v areaoaa the grinding wheel, are again slow down to a rate ultimately determinable by e adjustable 4 speed determining rheostat or resistance member 40.

From the foregoing description it will be seen that there has been provided an improved extremely compact and eflicient wheel speed determining mechanism, embodiable initially as a part of or alternativelyasan attachment for various types of grinding machines in which the speed determination is-directly controlled by a member engaging and gaging or measuring the diameter of the grinding wheel in place of being effected by remote control devices or adjustment of mechanically related parts which may or may not have the presumed prescribed relation to the actual wheel diameter.

It will further be noted that there has been provided a mechanism which is movable as an.

entirety with the grinding wheel during any adjustments of the grinding wheel, and adjustable with respect to the grinding wheel mounting or other mechanical elements of the machine only insofar as'and to the same extent as the decrease in size of the grinding wheel during operation and therefore operating are obviated. I

It will further be noted that an improved control circuit hasbeen provided by which excess peripheral wheel speed is at all times prevented, but which permits of any desired slowing down of the wheel speed for performance of a particu lar grinding operation.

It is further to be understood that the present invention relates primarily to the provision of control mechanisms for the rate of rotation or number of revolutions per minute of the grinding machine spindle including an automatic mechanism for varying the potential speed limits dependent on the wheel diameter, and additional mechanism for effecting speed variations within said limits and a third mechanism effective to" counteract-the first mechanism to the extent of making it possible to slow down the number of revolutions per minute below the limit otherwise established by the automatic mechanism.

It is further to be understood that while the particular type of speed control mechanism 11- lustrated for purposes of understanding'of the present invention has been shown as a variable speed motor in which the speed variations are accomplished by varying the electrical effect of the shunt field of the motor,.that it is contemplated other forms of speed varying mechanisms maybe employed in conjunction with my present improved controls. For example,the manually controllable or even the automatically controllable speed mechanism may be made inthe form" of shiftable change speed gears or an infinitely variable drive mechanism of either themechanical or hydraulic type, or that the motor mechanism itself may be a variable hydraulic motor,

such as the cam controlled commercially known Oilgear or other pump-motor device, and that the reactance of the control device coupled with the truing mechanism may be on the'throttle or the positioning of the speed determining cam of such a hydraulic device, within the scope of the succeeding claims without departing from or exceeding the present inventive concept.

What is claimed is:

1, In a grinding machine,-the combination with a grinding wheel and-avariable speed motor for effecting rotation thereof, of a truing device havwheel speed fluctuations ing a' followup movement whereby same may be eflectively projected into engagement with the periphery of the grinding wheel during reduction in diameter thereof, elect'rc-mechanical means for varying the speed of said motor, and operative connections between the truing device and said means for increasing the potential rate of motor operation as the .truing device'is moved in a direction toward the wheel.

. 2. In a grinding machine, the combinatibn with a grinding wheel and a variable speed motor for eifecting rotation thereof, of atruing device having a followup movement whereby same may be efiectively projected into engagement with the periphery of the grinding wheel during reducvariable-speed mechanism for 'efiecting rotation of the spindle, a-flrst rate adjuster for. selectively varying the rate of drive of. the spindle within prescribed limits, a second mechanismadjustable in accordance with variations in the diameter of the wheel for varying the limits effective by the first rate adjuster, and additional means for neutralizing the one of said rate adjusters to render same ineffective as respects spindle speed variation.

4. In a precision grinding machine th e combination with the grinding wheel, its supporting spindle, and means for eflecting rotation of'the spindle, of a truing device radially shiftable in thedirection of the operative surface of the wheel, a speed control mechanism, connections between said truing device and said speed'c'ontrol mechanism to vary the potential peripheral speed of the grinding wheel in accordance with the position of thetruing mechanism, and additional manually operable means for varying the actual wheel speed within the limits prescribed by the reaction from adjustment of the truing device on said first speed control mechanism.

5. In a precision grinding machine, the com bination with the grinding wheel, its-supporting spindle, and means for effecting rotationv of the spindle, of atruing device radially shiftable in the direction of the operative surface of the wheeL; a speed control mechanism, connections between said truing device and said speed control mechanism tovary the potential peripheral speed of the grinding wheel in accordance with the position of the truing mechanism, additional manually operable means for 'varying the actual wheel speed within the limits prescribed by the reaction from adjustment of the truing device on said first speed control mechanism, and an ad ditional control mechanism for effecting a sup plemental slowing down of the wheel speed. a

6. A control mechanism for the operating speed of a grinding wheelspindle including a variable speed drive for the spindle, a member positionable in definite relation to the operative peripheral surface of the grinding wheel, a first mechanism operative when said member is in projected position in'the presence of a large wheel to vol eiifecta reduced number of revolutions minute of the spindle, an additional mechanism operable when the member is in retracted position in correspondence with a smaller diameter grinding wheel for efiecting a corresponding increase in revolutions per minute of "the grinding wheel spindle, and an additional manually controllable mechanism for effecting corresponding variations in the number of revolutions per minute of the grinding wheel irrespective of the position oi! said first-mentioned member.

7. In aprecisior' grinding machine, includin a grinding wheel, a supporting spindle therefor, and a variable, speed motor coupled with the spindle for effecting rotation thereof, means for determining the speed 01 rotation oi the spindle and thus the peripheral speed of the wheel, in- I cluding a truing device incrementally adjustable in a'position peripherally'to engage and tom the face of the wheel, means for effecting incremental adjustments of said truing device, a control circuit. for the variable speed motor including serially interposable resistances, and cam means carried by and shiitable with the truing device ior determining the successive serial couplings of the resistances in the motor circuit,

whereby the potential rate of drive of the grinding wheel and spindle is automatically determined by successive adjustments or the truing device in the directional the operative face of the wheel. I r

- 8.;In a precision grinding machine, including and a variable speed -motor' coupled with the spindle for eilecting rotation thereof, means for -a grindingwheel, a supporting spindle therefor, P

determining the speed of rotation 01- the spindle and .thus the peripheral speed of the wheel 'including; a truing device incrementally adjustable in a'position. peripherally to engage and form the iace of the wheel, means for electing incremental adjustmentso! said t-r'uing device, a control circuit for the variable speed motor including serially interposable resistances, cam means .carried by and shiitable with the truing device for determining the successive serial couplings oi-the r in the motor circuit,

whereby the potential rate 0! drive or the grinding wheel and spindle is automatically determined by successive-adjustments or the truing device in the direction or the operative face of the wheel. and additional means in the motor circuit for varying the speed of themotor and thus oi .thewheel spindle within the limits. provided by said cam controlled potentialrate determining resist- 9.Wheelspeedcontrolmeansioraprecision grinding machine including a rotatable spindle pporting a wheel. a variable speed rno I for actuating said switch devices operatively to connect and disconnect the respective resistances with respect to the'motor circuit whereby difler- I -ent operating speeds of the motor are eiiected. and means for modiiying the electrical efiect of the variable resistance and thereby the actual speed of the motor within the range automatically imposed by the truing device cam and adjustment. of said resistance controllers. 10. In a machine of the character described, the combination with a grinding wheel spindle and a variable speed drivemotor therefor, of a motor actuating circuit including a plurality ofy serially employable motor rate determinators including afirst adjustable rate determinator in the circuit, a plurality of additional rate determinators, automatically operable=means for selecmovement therewith relative thereto, oi: means for automatically controlling the rate of rotation oi said grinding wheel including a variable speed drivemotor mechanically coupled with the grinding wheel for actuation thereof, a power circuit for the motor including a variableresistance speed control element and a plurality of fixed' resistance speed control elements, con-' nections between said fixed resistance elements and the truing device for effecting coupling 01 the circuit by way of or exclusive-of said fixed resistance elements dependent on the adjustment of the truing device with respect to the axis or rotationof the grindng wheel, and additional means tor coupling the circuit to the motor exclusive oi said fixed resistance elements -irre-' .spective of the circuit conditioningefiected .by.

movement of the truing device.

, 12. The combination withfa precision grinding machine'including a bodily shiitable rotatable grinding wheel and a truing device mounted for movement therewith and relative thereto; or means'ior automatically controlling the rate of rotation of said grinding wheel including a variable speed drive motor mechanically coupled I with the grinding wheel tor actuation thereof, apowei circuit for the motor including a variable matinee speed control element and a plurality.

of fixed resistance speed control elements, con-.

nections between said fixed resistance elements and'theotruing' deviceior'eiiectin'g coupling oi tor-for actuation 0! said spindle and a truing device support adjacent said wheel and-shittable thereof for truim operations andradi'alwithrespecttheretotoiollow'up the circuit by way of or exclusive of said fixed re- 'sistance elements dependent on the adjustment otthetruingdevicewithrespecttotheaxisor notation oi the vgrinding wheel, and additionalwheelasthediameter thereoiisdecreasedJa'id;

means comprising a plurality oi resistance elecuit'oi the variable motor, one of said re-,

.sistancesbeingoithevariabletype,switch devices determining the'eilective certain o! the raistances in'this circuit, controilers'tor said I switch devices, means including a cam'carried-by I and shiitable with the in its .mentscoupieableinseries-intheoperating cir-- caus and means for coupling the circuit to the motor exclusiv'e of said fixed resistance elements irrespectiveo! circuit conditioning eflectedbymovemeat of truing device, said truingedevice- "control including cam demerits carried by and movable with .the truing device and controllers individual tothe respective-fixed sep' independently operable by 9

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