US2791067A - Grinding apparatus - Google Patents

Description

May 7, 1957 J. J. FALLS GRINDING APPARATUS Filed Jul'y 12, 195e 2 Sheets-Sheet 1 INVENTOR. L/oH/vc/ FLLS f6?. 3, yBY j May 7, 1957 J. J. FALLS 2,791,067

GRINDING APPARATUS Filed July 12, 1956 2 Sheets-Sheet 2 l 45 46/43 3a a? 44 INVENTOR. 10H/v L/, FLLS United States Patent O GRINDIN G APPARATUS John J. Falls, Cincinnati, Ohio, assignor to The Standard Electrical Tool Company, Cincinnati, Ohio, a corporal tion of Ohio Application July 12, 1956, Serial No. 597,494

Claims. (Cl. 51-72) The present invention relates to grinding apparatus, and is concerned particularly with improvements in heavy duty machinery for the grinding of metal objects with the use of large grinding wheels. Grinders of the type herein disclosed are large and powerful, utilizing grinding wheels often supplied in thirty inch diameter sizes, driven at high speed by motors rated up to fifty horsepower, so `that the elements of safety, durability, dependability and economy of operation become important factors in the production and operation of such machines.

An object of the invention is to provide adequately for the protection of the machine operator and other persons in the vicinity ofthe machine, from the effects of grinding wheel fracture and explosion which sometimes result from overspeeding, or from wheel imperfections.

Another object of the invention is to provide means in association with a machine of the character mentioned, for electing maximum removal of wheel dust and metal particles from the operators station, for obvious reasons.

Another object is to provide, in connection with a variable speed drive for the grinding wheel, adjustment means for preventing attainment of excessive peripheral speed of the wheel which might result in fracture or disintegration, the adjustments being automatically and at all times co-ordinated with changing wheel diameters resulting from use and wear.

A further object is to provide means for maintaining in working order those movable parts of the grinding apparatus which are vulnerable to the clogging or deteriorating effects of flash and grit from the grinding wheel, thereby to eliminate servicing diiculties and shut-down time usually attributable to those elements.

Another object of the invention is to incorporate in the machine design such structure as will facilitate and expedite the changing of grinding wheels, and other servicing operations incidental to use of the machine.

A further object is to structurally compose the grinding apparatus in an improved manner, to relieve the grindf ing wheel shaft bearing housing of needless strain and vibration, thereby contributing to smooth operation of the machine and increasing its useful life.

Another object is to simplify and expedite manufacture and assembly of machines characterized as related above, and to incorporate certain improvements of structure whereby the machines are rendered compactY and Well balanced. Y

Y' The foregoing and other objects are attained by the means -described herein and illustrated upon the accompanying drawings, in which:

"Fig 1 is a right-side perspective view of the grinding apparatus incorporating the improvements of the invention.

Fig. 2 is a left-side perspective view of the same, fragmentaryA in character, and showing the wheel guard housing door detached in the interest of clarity of disclosure.

' Fi'gf 3 is aside elevational view of an adjustable wheel guard forming part of'v the invention. i y K Fg'.4 is a'fragmentary enlarged front view of the wheel ICC guard and guard housing, the position of the grinding wheel on its shaft being indicated by broken lines.

Fig. 5 is a side elevational view showing the motor drive for the grinding wheel, and linkage associated therewith to automatically adjust the wheel guard.

Fig. 6 is a front elevational view showing the tool rest of Fig. 1 and parts associated therewith.

Fig. 7 is an enlarged cross-sectional view taken on. line 7-7 of Fig. 6.

In the drawings, 12 indicates the main housing of the grinding apparatus, which supports the driving motor 10 and the bearing housing 13 for the grinding wheel shaft or spindle 14. The shaft carries the circular disc-like grinding wheel 15, which is fixed to the shaft for rotation therewith in the usual manner, as by means of wheel anges 16--16 which are clamped against opposite side faces of the wheel 15 by means of a nut 17 on the free end of shaft 14. The flanges keep the grinding wheel centered and ixed relative to the rotary driving shaft, in accordance with common practice in the art.

Above the grinding wheel is located a wheel guard 18, which is supported for sliding movement or adjustability from front to rear of the machine housing 12, this guard being supported in longitudinal spaced parallel ways or channels 19-19 formed in the side walls of a guard housing 2) and its displaceable door 21. The door may be mounted upon the guard housing for relative swinging movement, with the use of hinge pins 22 associated with the pairs of hinge barrels 23 and 24 carried by the door and the housing 20, respectively. One or more latches 25 of suitable design may be employed for securely holding the door 21 in closed position against the open side of the guard housing, thereby ensuring rigid and rm positioning of the guard channel 19 of the door relative to the similar guard channel of housing 20, for proper support of the wheel guard flanges 26-26 which extend outwardly from the guard side walls 27-27 to slidingly engage the channel.

The wheel guard 18, in addition to the spaced parallel anges extending outwardly from the side walls 27, in-

cludes also an arcuate top wall 28 curved in approxi-L mate correspondency with the grinding wheel periphery, and at its forward end portion 28 said top wall may carry an extending boss Z9 suitably bored or otherwise adapted for the mounting of an adjustable eye shield, not shown, but which is commonly applied to grinders for intercepting grit or other substances thrown from the grindingwheel by centrifugal action while the grinder is in operation. One side wall of the guard may be provided with a lug 30 extending at right angles there dinary forces directed at the guard, the additional metalof the guard housing top 31, rear 32, bottom 33, and front walls 34 may be depended upon to stop and contineiany grinding wheel fragments or sections thrown from the wheel shaft in the event of wheel breakage.

It may here be noted that double protection against injury to the operator is afforded by the wheel guard and the guard housing in the event ot' wheel dismemberment, the guard housing being highly effectiverfor the purpose due to the fact that it contines the major port tion of the wheel guard 18 and most of the mass of the grinding wheel itself. t

Another important feature involving the guard hours:A

iatented May 7, '1957.

avancer ing 20, `resides in the Afact that said housing is made integralwith or welded directly to the mainhou'sing of the machine, and` has no direct connection with the spindle Ibearing housingl In other words, lthe spindle bearing housing Aitself supports no part of `the wheel guard or 'any Wheel `guarding element which may become subject to 4impact or vibration during use of the machine, iso that as the result `of this construction all extraneous forces and strains are effectively divorced from the wheel "shaft or spindle, this being inducive Yto long spindle life with smooth and noiseless operation, and accurategrinding procedure.` 'ln Fig. 2, the spindle bearing housing 13 is seen to extend through an enlarged opening in one side of the wheel guard housing. Directing opposite the opening 35, a .hollow boss 36 on the door 21provides space for accommodating the spindle nut 17 when 'the door is closed.

Fig. l illustrates how a.full-size new grinding wheel is related to the guard 18 and other .elements of the ma chine. As the grinding wheel loses .diametral dimension due to wear, its peripheral speed decreases .and the grinding edge rccedes gradually from the interior of guard 18. To compensate for these variations, means are provided for increasing the wheel speed and at the same time readjusting the guard to the wheel periphery, these adjustments being co-ordin'ated so that the space lbetween the wheel and the front end 28 of the guard is determinative of, or `in ratio tothe speed of the wheel. Referring to Fig. 5, it is noted that drive motor 10 is mounted upon a base 37 which, guided on ways 38, may be shifted toward and from the wheel shaft or spindle 14. Shifting of said base may .be controlled manually by rotating a handwheel 39 `at the front wall 40 of the machine, said handwheel beingxed to a shaft 41A extending` through wall toward the motor base. By means of a fiexiblecoupler 42, the handwheel shaft may be connected to a rotatable screw 43 which engages a nut` 44 fixed to the motor base. The shank of the screw may be joumaled in a bearing 45 fixed relative to the main housing ofthe machine, and precluded from .lengthwise movement through the bearing by means of collars 46-46 or otherwise.

From the foregoing, it will be evident that rotation of the screw by means of handwheel 39 may shift the motor 10.and its base 37 toward the spindle 14 and the pulley 47 thereon. When this occurs, a variable drive pulley 48 on the motor shaft is `permitted to contract in a manner well known, for increasing the effective diameter of the drive pulley, which in turn speeds the linear travel of belt 49, with resultant increase in `,the speed of driven pulley `47 `and the .spindle .14. At the .same

time, movement of the motor base is transmitted to the` wheel guard 18 through the linkage comprising .the adjustable rods 50 and 51, each of which has an end pivoted to a. lever 52 at the locations 53 and 54. Lever 52 may rock about a pivot fixed to the guard `housing as shown, and the remaining ends ofthe adjustable rods are pivoted at 56 and30 to the motor base and the wheel guard, respectively. Therefore, as the motor base 37 is moved toward the left in Fig. 5, the vguard 18 is shifted toward the right, bringing the forward end of the guard into close relationship with the grinding wheelperiphery, thereby to properly adjust the guard to the worn grinding wheel.`

The operator in rotatingthe .handwheel l39 clocltwise, positions the front end of `the guard as closely as possible `to the grinding wheel `edge, .leaving aslightclearance, and in the course .of such manipulationthe spindle speed vautomatically will ,be increased `as `above explained. Underno uconditions could Athe Voperator foverspeed the spindle, V.for to `do .so wouldfnecessitate driving .the forward endpf .the..guard 18 4intothe periphery of vv.the wheel, :which .of courseiindicatesfatfonce .an ob vions maladjustrnent. With the arrangement fdisclosed,

therefore, adircct andproper izo-ordination Aiscassured be tween any given diameter of the grinding wheel, its speed ofr'ota'tion, vand the position of the adjstable guard relative to the grinding wheel. It may here be noted that the guard housing side wall is slotted as at 57 to permit shifting of the guard stud 30 with the wheel guard incident to adjustment of the latter as above explained. An enlarged collar 30 xed `.on the stud 30, bears against the outside of wal1t20 to --hold the lwheel guard in place with respect to wall 20 and its channel 19, whenever the `access door r21 `is .swungto the open position. The collar `may lbe provided with a notch or other t-ype of indicator as shown, to indicate various grinding wheel speeds imprinted orotherwise applied `to the guard housing along the slot 57.

The linkage between the driving motor and the wheel guard, and the nature of the pulley speed changer, are subject to modifications and substitutions within the skill of the engineer or designer. `Withregard to the .particular `mode of assembly illustrated, wherein the `driving motor ,is placedimmediately `behind the guard housing 20, upon the machine frame, it should readily be evident that acompactness of ,structure is achieved which makes possible a squaring of the machine base with improved proportions, lresulting in a substantial saving of valuable oor ,space required `in -setting .up the machine for use. Moreover, `the motor with "its bulklocated `in line with the probable course of flying wheel fragments in the event of wheel disintegration, will furnish a highly effective `stop or barrier minimizing the likelihood of injury to persons working tabout `or behind the mach'me.

To further advance the 4safety and eiciency considerations ofthe machine, means are provided for achieving maximum wheel enclosure at the front of the machine. This is effected by `forming inturned spaced parallelanges 58 and 59 onthe door 21 and guard housing 20, said flanges "being 'disposedin a commonplane transverseto the guard lchannels and extending from said channels downwardly toward the bottom wall of the guard ,housing. -The anges 58 yand 59 .are cut away and shaped at their-opposinginner edges to fit about the wheel anges 16-1'6 with slight clearance, as clearly Iindicated upon Figs. 1 and 4, while the remaining upper -and lower portions ofthe fianges 'closely hug 'the sidefaces of the grinding wheel without actual contact. By so enclosing the grinding wheel. at the front fof the housing 2.0, the .danger resulting from wheel fracture is greatly minimized, and at the same time anv improvement is .noted in the effectiveness of the system 'for controlling and removing dust and grit from the region of the operators ystation at the `front ofthe machine. The'dust removingsystem comprises a source ofhegative air pressureinthe form of a blower or fan,'no't shown, connected by ductwork lin usual, manner to theexhaust'outlet port 60 formed in a wall of the guard housing (Fig. '2), to maintain movement of air past the wheel and fromjthe'housing while the grinding apparatus is-in operation.

Mounted atthe front `of the machine is an improved tool "rest "assembly, comprising an angular rest 61 adjustable as to elevation relative to 'a bracket 62, which bracket may bekeyed or otherwise fixed to a support'bar 63 extending ksubstantially .horizontally from the front wall 4 0ofthe mainhousing or frame of the machine. Vertical adjustment ofthe tool rest may be provided for in ,anysutable manner, as by means of stud screws 64 `anchored in 'the base 65 of the bracket andextending through an elongate slotv 66 inthe verticalleg ofthe rest.

vNuts applied to thestudiscrewsas `illustrated by-.Fig r6,

the 'braeketimay include'a Aboredlmss 67 receptive I of the v-outeriend:.ofithcbar, and .to which'thmbossishxed against relative movementsasprevicuslyfstated. The-:bar .has` an vinnerend `sliding ,received 1in a -bored boss or; hearing 69 integral with or xed to the front wall of the machine housing, and in this bearing the bar may be shifted lengthwise to advance rand retract the tool rest 61 relative to the working face or edge of the grinding wheel. A key 70 or other suitable means may be applied to the bar and boss 69, to preclude rotation of the bar relative to said boss.

Axial shifting of the bar 63 may be achieved by direct manual application of force, or if preferred, mechanical means may be employed for the purpose. An example of such mechanical means is disclosed by Fig. 7, wherein 71 indicates a lead screw having its threaded portion received in a nut 72 fixed to boss 69 in concentric relation to a bore 73 provided in the boss. The bore 73 is parallel to the bar 63, and at substantial right angular relationship to the front wall of the machine housing. The opposite or outer end portion 74 of the screw may be journaled for rotation in a bearing 75 of bracket boss 67, said bearing being in axial alignment with nut 72. A shoulder 76 and a collar 77, or any equivalent means associated with the lead screw, may be employed to preclude axial movement of the screw through the bearing 75 as the screw is rotated in one direction or the other to advance or retract the bracket 62 and the tool rest carried thereby. The terminal end 78 of the screw may be adapted to accommodate a crank '79 or other tool for convenience in rotating the screw.

Since the tool rest support bar and screw 71 are necessarily located in close proximity to the grinding wheel, or in position to intercept grinding grit and flash from articles undergoing grinding, it is considered desirable to cover and protect those elements in order to prevent accumulation of such foreign materials thereon. It is found that the grinding grit and the metallic flash require separate treatment for the control thereof, because of their differing characteristics. For example, the flexible impervious boot Sil employed to envelop and confine the bar and screw to protect them from grinding grit and dust, may not be expected adequately to withstand the heating or burning effects of flash from steel objects undergoing grinding, nor would the boot be easily cleaned of flash material because of the adherence power of the latter when hot and in a partially molten state. For proper control of flash, it should be intercepted by a smooth and extensive metallic sheet which is exposed for easy cleaning by scraping. Flash material which would be difficult to remove from the work rest support bar and screw 71,

particularly if partially fused thereon, is easily accessible for removal by scraping from the flash interceptor hood indicated at 81 upon the drawings.

The flash interceptor hood may comprise a sheet of metal initially rectangular in form, curved in one direction to the shape of an approximate quarter-cylinder, one end of which is provided with an inwardly directed flange S2 to butt against the inside face of bracket 62. By means of screws 83 or other fasteners, the flange 82 may be secured to the bracket so as to ensure bodily movement of the hood with the bracket and the tool rest support bar 63. At the inner end 84, the hood extends through an arcuate slot 85 formed in the front wall of the machine base or housing 12, said slot being preferably of approximate quarter-circle extent, or of sufficient length to accommodate the hood in its movements through the machine front wall. The hood is to overlie the support bar 63, and depend downwardly at the tool rest side of the bar so as to intercept flash and grit directed down wardly by the rotating grinding wheel. The outer face of the hood should be smooth to facilitate cleaning, and discourage fusion of flash thereto.

To a major extent, the metallic hood 81 may cover the boot or flexible protector $0 which surrounds the support bar 63 and screw 71. Said boot may be in the form of a cylindrical pleated tube of flexible material (Fig. 7), collapsible in the direction of its length in simulation of an accordion, with opposite ends 37 and 88 thereof fitted nectionsat the ends-thereof, and the intermediate 'portion of the boot surrounding the bar 63 and its adjusting screw, l

the movable fitted parts of the tool rest assembly are fully protected against undue wear and possible binding, with the result that the tool rest assembly is easily and smoothly manipulated at all times, no servicing being required. As will be understood, the tool rest may be advanced by means of the adjusting screw 71, to assume a proper relationship to the working face of the grinding wheel at all times as the wheel diameter decreases due to wear. In all positions of the tool rest assembly, full protection of the working parts is furnished by the boot and the overlying metallic hood 81.

From the foregoing explanation and disclosure, it readily will be appreciated that the structural improvements incorporated in t he grinding apparatus possess considerable merit, to the ends that efficiency and economy of operation, convenience, and safety are advanced to an extent heretofore unattainable in the grinder art. The improvements specified reduce servicing and shutdown expenses to a practical minimum, and the replacement of grinding wheels is greatly facilitated and expedited, with substantial savings of time and labor. Various other advantages and objectives will become manifest to those skilled in the art to which the invention appertains.

lt is to be understood that various modifications and changes in the structural details of the machine may be made, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed is:

l. Grinding apparatus of the class described, comprising in combination, a main frame having a bored and slotted front wall, a grinding wheel rotatably supported on said frame for movement in a plane normal to said front wall. a tool rest in the plane of said grinding wheel, and tool rest support means comprising an elongate bar having an inner end slidable in the front wall bore, and an outer end supporting the tool rest, a collapsible protective boot of flexible material surrounding the bar to intercept grinding grit flung from the wheel when rotating, and a flash intercepting hood of metal overlying the protective boot, said hood being movable with the bar and slidable through the slot in the main frame front wall.

2. Grinding apparatus as specified in claim l, wherein the boot is of tubular substantially cylindrical form, and the flash intercepting hood is arched to conform substantially with the contour of the boot.

3. Grinding apparatus of the class described, comprising in combination, a main frame having a bored and slotted front wall, a disc-like grinding wheel rotatably supported on said frame for movement in a plane normal to said front wall, a tool rest in the plane of said grinding wheel, and tool rest support means comprising an elongate bar having an inner and an outer end, the inner end being supported for sliding movement in the front wall bore, a bracket fixed on the outer end of the bar, and means adjustably securing the tool rest to the bracket for bodily movement therewith, a collapsible protective boot of flexible material tubular in form, completely surrounding the slidable bar, and having opposite ends fixed respectively to the bracket and to the front wall of the main frame about the bore therein, and a flash intercepting hood of hard rigid material overlyingV the protective boot, said hood having an inner end portion slidable within the slot of the frame front wall, and an outer end fixed to the bracket, whereby the hood moves with the bracket along a line parallel to the axis of the bar, and means normally precluding rotation of the bar within the front wall bore.

4. Grinding apparatus as specified in claim 3, wherein the tubular boot is substantially cylindrical in form, and the flash intercepting hood and the front wall slot are meme? arcuate in crosssection,in substantial `conformity with the contour Aof the boot.`

5. Grinding `apparatus of the class described, comprising `in combination, a nmain frame having -a bored and arcuately slotted `front wall, a disc-like grinding wheel rotatably supported on said frame for movement in a plane `normal to said front wall, a tool rest in the plane of -said grinding wheel, and Atool rest support means comprising an elongate bar having an `inner end and an outer end, the inner end -being supported for sliding movement inthe front wall bore, a bracket fixed on the -outer end of the bar, and means securing -the tool rest to the bracket for bodily movement therewith, means for advancing and retracting the bar axially toward and vfrom the front wall of the frame, comprising `a screw journalled in the bracket `for rotation and having a threaded end directed toward the yfront wall in parallelism with the bar, and an outer end exposed at the bracket, a nut fixed tothe front wall accommodating the threaded end of thefscrew, to' enforce linear movements of the bracket and bar as the screw is rotated, a collapsible protective boot of flexible material tubular in form, completely sur rounding the slidable bar andthe threaded end ofthe screw, said boot having opposite ends xed respectively tothe bracket and to the front wall of the main frame,

S and an arcuate ash intercepting hood of smooth metal overlying fthe protective boot, said hood having an arcuate inner end portion slidable within the arcuate slot of the frame front wall, and an outer end fixed to the i bracket, whereby the hood moves `withthe bracket along a line parallel to ythe Aa-xis of the bar.

References Cited in the tile of this patent UNITED STATES PATENTS 863,643 Ransom Aug. 20, 1907 1,217,996 Partridge Mar. 6, 1917 1,694,340 `Wineland Dec. 4, 1928 1,891,696 Trimble ---5 Dec. 20, 1932 1,911,857 `Stumpf May 30, 1933 1,923,160 Smith Aug. 22, 1933 2,003,495 Ritz June 4, 1935 2,130,823 Wilson 05. Sept. 20, 1938 2,294,153 Alvord Aug. 25, 1942 2,471,561 Fielding c May 31, 1949 FOREIGN PATENTS 445,621 Great Britain Apr. 16, 1936 479,074 Great Britain Jan. 3l, 1938 1,052,587 "France Jan. 26, 1954 it "A"

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