US2373336A - Grinding machine - Google Patents

Description

A ril 10, 1945. w. w. PERKINS ET AL GRINDING MACHINE Filed April 18, 1941 3 Sheets-Sheet l I III I. II. Ill .1!!! vllllllllll'll llflfl l I;

3 Sheets-Sheet 2 April 10, 1945.

w w. PERKINS ET AL GRINDING MACHINE Filed April 18, 1941 April 1945- w. w. PERKINS ET AL 2,373,336

GRINDING MACHINE Filed April 18, 1941 5 Sheets-Sheet 3 1NVEN TORS Wm: w PM BY M 9.3%... QLM LLL a;

Patented Apr. 10, 1945 2,373,336 GRINDING Walter W.'P'erkins, and Ellsworth Annis, Sa1em,.

Mass, assignors -to Reid Brothers Company, Inc, Beverly; Mass:-,acorporation of Massachusetts Application April is, 1941, Serial No, 389,184

7=C-laims; (cusp-a3) This invention relates toia grindingimachine and. more particularly to a surface grindingimachine.

The invention has for an objectto provide-a novel and superior surface grinding machine which may be economically manufactured? and assembled and is of improved-construction embodying novel driving. mechanism, wherebytoenable the machine to operate in an accurate, positive and smoothly operating manner, 1

With this general object in View an-dlsuch others as may hereinafter appear, the invention consists in the grinding machine-and-ain;thevarious structures, arrangements-and: combinations of parts hereinafter described and particularly defined in the claims at the end ofdthis specification.

In the drawingsillustrating the preferred em;- bodiment ofth invention, Fig, 1 isa plan View, with portions broken away, of a, grinding-ma,- chine. embodying the presentinvention; Figs,--2 and 3am detail views of driving connections to the cross feed mechanism, to be referred to; Fig. 4 is a front elevation, partly in cross-sectiomof the machinesho-wn in Fig, 1; Figs. 51 and,-6 are detail views intransverse and longitudinal. crosssection respectively of a drivingdrum .forming a part of the driving mechanism, to bereferred to;

Fig. 7 is a side elevation; partly in: cross-section, of the grinding machine .emb'odyingtha-present invention; and Fig. 8 is. a' wiring-diagramillustrating the control mechanism .for controllingthe driving, mechanism, as hereinafter described.

In general, the present invention contemplates a novel and improved surface grinding machine provided with a longitudinally reciprocable-work supporting table for holding and moving the parts to be machined relative to a grindingwheel, and which is also provided with cross :feed'mechanism for progressively moving theworkL-supporting table in a transverse directionrelative towthe grinding wheel.

In accordance with oneieature oftherpresent invention, provision is made for operatingthe reciprocable work supportingi'ablev through connections from a .reversing ,motor arranged .,to be controlled by the movementofthetable; -Provision isalso maderin thQrIIlOtOL. circuit Treadecreasing the starting torque .of thereversing motor whereby to reduce the shock incident to the change in direction and totcontributetimproducing smoother tableoperation.- Asa further provision for assuring smooth andsubstantiaIIy vibrationless table operation,.,the con'nectidngto the table may include steel'b'ands'v or straps an ranged to be alternatively r wound and unwound upon admin, as. will be described.-

Other novel features of the present invention, to be hereinafiter described; comprise lmechanism of novel structure for disengaging the motor attachedtouthe machine in. completelyyassembled form, as will be hereinafter more fully-described. 4 Referringnow to'thev drawings, and particu-. larlyto. Fig, 4, the grinding machine: indicated generall-yat i0 is provided with: a; grinding wheel I2 andv'a longitudinally reciprocable Work-supporting. table 14. The worksuDpor-ting table is mounted to slide longitudinally upon ways I5, l8 provided in across slide-20 which, inturn; is adapted. to bemovedntransversely in waysczl, 24, formed-in the top; of ,a: casing 26 mounted upon the base 28? of the ma*chine. The:gri-nding wheel. I2 is mounted upon aspindle iii and is independently driven by. alspindle motor [5, as

shown in Fig 7.

The work supportingtableolll is arranged to. be

reciprocated through .connections includinga driving pulley or drum 30'I nd.v two steelbands or straps 32, 34, eachof which isconnectedat one endto thedrivingdrum, asillustratd'in detail in Fig. 5. The other ends of the straps extend over idlerpulleys. 36,v 38 respectively, and are connected to lugs 40, dzdepending from the opposite ends. of the table as. shown in Fig. 4. The idler pulleys 36, 38 are. rotatably mounted uponstuds 4'4, filfisupported; inthe crossslide 20.

Provision ismade for driving and'reversing the rotation of thedrum 30 cause the straps 32, 34' to alternately wind and. unwind onv the drum to efiect reciprocationloil'the table. 14 through connections from a reversing motor 50 as shown in Figs. 1 and 4... The drum 3!] .is mounted .upon and arranged to rotatewith a driving shaft, 52 journaledin. suitabldbeaflngs 54; 56 mounted in the machine frame. Theshaftiz 'is' provided with a gear 58Tfast thereon which is arranged to mesh with a. .pinion'fifl. formed integrally with a clutch member 62 rotatablymounted and longitudinally'mouable upon a shaitfi l'. The'clutch clutch member 62 is arranged to engage a coop erating member 80 fast on the shaft 64, which latter is provided with a hand wheel 82 at its outer end. The shaft 64 is jburnaled in a bear ing 83 formed in a bracket 84 detachably secured, to the casing 26. The movable clutch member 62 is moved longitudinally to engage and disengage the clutch connections 6 5, 80 byh s'hifter member 86 adapted to be actuated through connections to a hand lever 80, as illustrated in Fig.'1. The pinion 60 is made wide enough to cooperate with the gear 58 in either of its longitudinally movable positions. As herein shown, the clutch shifter unit, indicated generally at 90, is carried by thedetachably mounted motor bracket I2 to form an assembled unit therewith.

From the description thus far, it will be observed that the detachable bracket 12 carries the motor driving mechanism and the clutch shifting mechanism as a completely assembled unit which may be convenientlyassemblecl prior to attachment to the casing 26 of the frame. This feature of the invention saves time in the assembly operation, renders the parts more accessible for replacement and repair, and results in econlongitudinally re'ciprocable work table in a transverse direction during the operation of the machine. As herein shown, the cross slide is provided with a bracket 06 attached to and depending from the underside thereof. 7 A square a threaded screw 98, secured at one'end to the bracket 96, is arranged tobe received in an internally threaded bushing or hollow shaft which in turn is rotatably mounted in a hub I02 formed in the casing 26.

Provision is made for intermittently rotating the hollow internally threaded shaft 1 00 in either direction to effect transverse movement of the table during the operationof the machine. As herein shown, the hollow shaft is arranged to be rotated through connections including a crank member I04, a rack I06 connected to and arranged to be reciprocated' by the crank, and a gear I08 loosely mounted on the hollow shaft and cooperating with the rack I06. The loosely mounted gear is formed integrally with a pawl carrier IIO upon which is mounted a double pointed pawl II 2 arranged to cooperate with a square toothed ratchet Il4 keyed to the hollow shaft, as illustrated in Fig. 2. Provision is made for adjusting the double pointed pawl II2 to engage either one or the other of the points with the square toothed ratchet, or to position the pawl in a neutral position. Such adjustment may be effected througha spring pressed ball arranged to be received in depressions in the carrier, as indicated at H6 in Fig. 2, and may be moved from one position to another by rotating the knob II8. A hand wheel II9 also secured to the hollow shaft I00 is provided to permit manual operation of the transverse mechanism when the pawl I I2 is in neutral position.

In operation, when it is desired to effect intermittent rotation of the hollow shaft I00 in a counterclockwise direction, the pawl II2 may be positioned as indicated in Fig. 2 so that when the pawl carrier I I0 is rotated in this direction by the reciprocating rack I06 and the gear I08, the pawl H2 in engagement with the ratchet will rotate the hollow shaft in a counterclockwise direction. Onthe return stroke of the rack I06, the pawl will slide over the ratchet teeth. It will be clear that when the pawl is positioned to engage the second point thereof with the square toothed ratchet, rotation of the hollow shaft I00 in the reverse direction will be effected. Thus it will beseen that the internally threaded hollow shaft I00 in cooperation with the square threaded screw is operative to effect transverse movement of the cross slide 20 and the table I4 supported thereon, in either direction during the operation of the machine. As illustrated in Figs. 1 and 2, the reciprocated rack I06 is received in a guide I 20 formed integrally with a sleeve I22 loosely mounted upon the hollow shaft I00 to permit relative movement of the supporting sleeve I22 during the angular movements of the rack. I06 as reciprocated by the crank I04.

Referring now to Figs. 1 and 3, the mechanism for rotating the crank member I04 will be described. As therein shown, the crank member is clamped fast upon the end of a stud I 24, rotatably mounted in a bearing I26 formed in the bracket 84. The stud.l24 extends from and is formed integrally with a pawl carrier I20 in which twopawls I30, I32 are mounted and arranged to cooperate with a square toothed ratchet I34. The square toothed ratchet I34 is formed integrallywith and is arranged to rotate with the driving gear 58. As above described, the driv ing gear58 is arranged to change its direction of rotation during the operation of the machine. Thus, in operation, when the ratchet I34 is rotated in a clockwise direction, the pawl I30, see Fig. 3, will be operative to rotate the crank through a predetermined stroke until the tail of the pawl engages a pawl stop I36 extending from the bracket 84, see Fig.' 7, to disengage the pawl I30 from its ratchet I34. Thereafter, during the remainder of the clockwise movement of the ratchet I34, the other pawl I32 will slip over the ratchet teeth. When the direction of rotation is changed, the pawl I32 becomes effective to rotate the crank as above described, until it in turn is disengaged from the ratchet by the pawl stop I36. Thus it will be seen that each time the crank is rocked in either direction the rack I06 is reciprocated to effect rotation of the hollow shaft I00 in the desired direction as determined by the adjusted position of the double pointed pawl II 2'. The rack I06 is secured to the crank I04 in a T-slot I05 to permit convenient adjustment of the length of stroke.

From the description thus far it will be observed that the detachable bracket 84 carries the crank ,driving mechanism and the connections for manually operating the machine as a completely assembled unit which may be conveniently. assembled prior to aifixing the bracket to the casing 26... Thus, the assembly of this portion of'the machineis facilitated, the parts rengar-gees dered' more accessible for adjustment or replace-- ment and the structure results in economy-- in manufacture.

Provision is made for permitting lateral movement of the driving drum on its'shaft 52fduring the transverse movement of the cross slide 20. As herein shown, the shaft 52 is provided with three raceway's I 30 in which ball bearings I42 disposed in the drum 30 are arranged to run.- As shown in Fig. 6, the ball bearings are retained in the drum by spring wire rings I45 arranged to be received in grooves I84 provided in the drum. The rings may be open to enable them to'be contracted and forced into the grooves where'they may again expand into a position toprevent-escape of the ball bearing members from thedrum. Thus, it'will be seen'that the bearing member's I42 serve as a driving .connection between the shaft 52 and the drum 30 and also permit lateral movement of the drum in a smoothly operating manner, thus reducing friction and tendency to bind on the shaft to a: minimum. As shown in Figs. 1 and 4, the bracket 96, attached'to the cross slide 20, is provided with arms Hi8, I48 arranged to embrace the drum 3lI-and to move it along the shaft 52 in alignment with the-longitudinally reciprocable table I4 as the cross slide is moved transversely.

Referring now to Figs. 4 and 8, provision is made for controlling the reversiblemotor 'to effect a change in direction of rotation thereof through connections from the reciprocable work table I4. As herein shown, a reversing switch I50 mounted in the cross slide 20 is arranged to be op-' erated by dogs I52, I54, adjustably supported upon and movable with the table I4. The reversing switch comprises a slidingly mounted stud I56 arranged to be reciprocated by a'pivotally mounted arm I58 which isreceived in a slot in'the stud I56. An operating arm I60, fast on the pivot shaft I62 is provided with pins I64, I65, arranged to be engaged by the dogs I52, I54, respectively at the end of the predeterminedlongitudinal movement of the table. The switchstud I56 is provided with contacts I60, I10 and in operation, when a dog engages the switch I50, it operates to first open the prevailing circuit to the motor- 50 and then close a second circuit to operate the motor in a reverse direction. A handle IBI is also provided on the operating arm I60 to permit the switch to be manually operated when desired. A safety switch, indicated at I12, may also beprovidedto be operative to open the entire circuit'in the event the dogs I52, I 54 are removed or become loosened; As illustrated in Fig. 4, cam pieces 7 I14, I16 supported on the underside of the table I4 are arranged to engage and depress the switch member I12 to open the circuit at contacts I18 when the the current through the motor so that its direc'- tion' of rotation isrevers'ed. The safety switch 1 contacts are indicated at I18 and a manually op-z table overrides or fails to engage the reversing switch I50. The reversing switch may and pref-, erably will be of standard construction capable of adjustment to control the rapidity of reversal. As illustrated in Fig. 8, the wiring diagram therein shown includes connections to the grinding head motor I5, and to the reversing motor 50. Stop and start switches I82, I84 are arranged to open and close a circuit to a primary magnetic switch I85 which closes the circuits to the grinding head motor and to the reversing motor at contacts I86, I81, I88 and I89. The reversing switch, indicated at I50 operates to alternately open one circuit and close another to the magnetic switches I90, I92 for alternately opening and closing the circuits to the reversing motor 50 at contacts I94, I95, I96, I91, whereby to reverse the direction of erated switch,l98 may also be provided for openingthe' circuit to the reversing switch I50.

As illustrated in Fig. 8, the circuits to the reversible motor 50 are provided withresisto'rs'ziln which operate to reduce the starting voltage and thus to decrease the starting-torque of the motor whereby the shockat the end .of the table'movement as it changes directions is reduced to a minimum thus'efiecting smooth and substantially vibrationless table operation;

From the above description it will be seen that the novel structure of the present surface grinding machine enables the machine to be operated i in the reciprocable driving mechanism assures'a substantially smooth and vibrationless movement of the table eliminating the effect of impulses caused by the usual gear and rack, or chain and sprocket forms of reciprocable drive heretofore used. All 'of the foregoing cooperate to impart the maximum smoothness in operation. vision of independently assembled units in the machine also effects-an economyin the production of the machine.

While the preferredembodiment of the invention has been herein illustrated'and described, it will be understood that the invention may .be embodied in other forms within the scope of the following claims.

Having thus described claimed is: I

'1.- In a grinding machine, in combination, 'a grinding-element, a work supporting table, driving mechanism for reciprocating said tablewith relation to said grinding element including a single drum mounted to be capable of rotation the invention, what is in opposite directions, two flat metal bands conand said drum'for effecting lateral movement of the' latter during "movementxo'f the cross. slide. 2. In a grinding machine, in combination, a

reciprocable work supporting table, driving mechanism for reciprocating said table including a reversing motor, a single drum mounted to be capable of rotation in opposite directions, two flat thin and flexible metal bands connected to different ends of said table and to said drum arranged to be alternately wound and unwound on said drum to effect reciprocation of the table, control means for effecting reversal of said driving mechanism, and operating connections between said control means and said work sup-v The pro- I porting table arranged toeifect said reversal: when the table is moved a predeterminednistance in either direction, a cross slide uponwhich .said table is mounted, means operativelyconnected to said driving mechanism foreffecting transverse movement of said cross slide, and connections between said cross slide and saiddrum for effecting lateral movementof-the latter .during movement of the cross slide. r 1 7 l 3. Ina grinding machine, inpombin-atiomza longitudinally reciprocable work supporting table, driving mechanism for reciprocating said table including a reversing motor adapted -,;to -;be connected to a power source for 'drivingsaid motor, means for automatically controlling: the operationof said motor, and connections between saidr -controlameans and said :work supporting table arranged to efiect reversal of said-, motorwhen the table is moved'a predetermined dis,- tan'ce in eitherv direction, a a cross slide upon which said longitudinally ireciprocablea work tableiis mounted, and means operatively connected to said driving mechanism for effecting transverse movement 'of said hoross .-slide, an auxiliary meansarrangedsto be: engaged.- lqy; the table for disconnecting :said; motor from said source of power to stop themachine in theievent that the table'overrides said -predetermined dis. tance, said auxiliary means comprising a single switch disposed substantially: centrally 'of the machine, and connections between said cross slide and said drivingmechanism for effecting lateral movement of the latterduring operation of said cross slide. was- 4; In a grinding machine, in combination, a longitudinally reciprocable work supporting table, driving mechanism for reciprocating said table including a, reversing motor, adapted to be connected to a power source for drivingsaid motor means for automatically controlling the operation of said motor, and connections between said control means and said work supporting table arranged to effect reversal of said motor when the table is moved a predetermined distance in either direction, across slide upon which said longitudinally reciprocable work table is mounted, and means operatively connected to said driving mechanism for. progressively advancing or retracting said cross slide transversely during the reciprocation of said table, an auxiliary means arranged to be engaged-by the table for disconnecting said motor from said source of power to stop the machine in the event that the table overrides said predetermined distance, said auxiliary means comprising a single switch disposed'substantially centrally of the machine, and connections between said cross slide and said driving mechanism for effecting lateral moveasyasse table, including a shaft mounted to be capable of rotation in opposite directions, a drum mounted to rotate with and to move laterally upon said shaft, two flexible fiat metal tension mem bers connected to different ends of said table and to said drum arranged to be alternately wound and unwound on said drum to effect reciprocation of said table, a cross slide upon which said table is mounted,-means ,operatively connected to said driving mechanismfor effecting transverse movement of said cross slide, and connections between said cross slide and said drum for effecting. lateral .movement of the latter upon said shaft. v

6.v In a grinding machine, in, combination,. a longitudinally reciprocable work supporting table, driving mechanism for reciprocating said table including a shaft, mounted to be capable of, rotation in opposite directions, a drum mountedto rotate with and to move laterally upon said shaft, two flat metal bands connected to different ends ofsaid table and to said drum arrangedto be alternately wound andunwound onsaid drum to effect reciprocation of said table, a cross slide upon which said table is mounted, means operatively' connected to said driving mechanism for effecting transverse movement of said cross slide, and connections between said cross slide and said drum for effecting lateral movement of the latter upon said shaft, said drum being provided with ball bearings, said shaft being provided with a plurality of longitudinally disposed raceways arranged to receive said ball bearings whereby to provide a driving connectionbetvveen said drum and said shaft and to facilitate lateral movement of the drum on the shaft. 7, r t

7. In a grinding machine, in combination, a reciprocable work supporting table, power driving mechanism for reciprocating said table including a motor, a power driven shaft, worm and worm gear connections between said motor and said shaft, a clutch member mounted on said power driven shaft, manually operated mechanism, for reciprocating said table including a manually rotated shaft provided with a handle, said manually rotated shaft being separate from and in end to end alignment with said power driven shaft, a second clutch member mounted on said manually rotated shaft, an intermediate clutch member shiftingly mounted on said manu-v ally rotated shaft arranged to be moved into operative en ement with said power driven clutch member orsaid manually operated clutch member, driving connections between said intermediate a clutch member and said table, and means for shifting said intermediate clutch member to convert the machine from said power driving mechanism to said manually operated mechanism. j o

WALTER. W. PERKINS.

ELLSWORTH ANNIS. p

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