US2438203A - Grinding wheel - Google Patents

Description

March 2 3, 1948.

L.. F.IcARR 2,438,203

GRINDING vWHEEL Fjil'ecll 4June 11 1945 Patented Mar. 23, 1948 UNITEDsTATEs yPATENT GFFICE 3 Claims.

One of the objects ofthe present invention is. to provide a novel end face grinding element which has a rapid cutting action and which is adapted for heavy duty operation. Y a

' Another object is to provide a new and improved end face grinding wheel which has a noncircular center opening, and which is formedin a unitary or single-piece structure closed throughout the circumference. l

A further object is to provide a novel abrasive grinding wheel which has a continuous end face about a non-circular center opening operative to hold and agitate the liquid coolant and to direct the latter to the surface being ground.

Other objects and advantages will become apparent as the description proceeds.

In the accompanying drawings,

Figure 1 is an outer end face view of a grinding wheel embodying the features of my invention.

Fig. 2 is a diametrical sectional View of the wheel taken along line 2-2 of Fig. 1.

Fig. 3 is a fragmentary sectional view, on an enlarged scale, taken along line 3-3 of Fig. 1.

Referring more particularly tothe drawings, the grinding wheel, constituting the exemplary embodiment of the invention, comprises a rotary` grinding element I made of bonded abrasivev material adapted to wear or break away in use. The element l is of the. general type having a com pletely closed, peripheral wall defining a narrow circumferential end face 2 about a central'recess or opening 3. Although not limited to any particular sizeor use, this type of wheel usually is made comparatively large in size, and supported for relative transaxial movement in va shear cut across the surface of the work in heavy metal removing operations.

Conventional ring wheels heretofore have been provided with a concentric cylindrical opening dening an annular end grinding face of uniform radial width throughout the circumference. such construction, the grinding face has a uniform resistance to wear throughout its area, and all of thecircular lines of cut are continuous and uninterrupted. Liquid coolant supplied .to the central opening can enter. between the grinding face and the surface being ground only in small amounts and with difliculty. By reason of these factors, the rate and efllciency of the cutting action are considerably impeded, andthe work is not always finished with the desired degree of surface smoothness. I,

The grinding element I of the present invention preferably also has .a continuous yor uninterrupted external cylindrical surface 4, but is provided with a central opening 3 'of non-circular shape. Within the broad aspects of the invention, various non-circular shapes may be employed provided they are symmetrical and centrally located to afford dynamic balance. Preferably, the opening 3 is multi-sided, for example with three or more straight sides suitably joined at the contiguous ends to provide corner areas projecting radially outwardly across the innermost circular lines of cut. More particularly, the opening` 3, in the specific form shown, is substantially square, with four straight flat sides 5.

The square center opening 3 materially innuences the shape and cutting characteristics of the circumferential end face 2. Thus, each of the sides 5 of the center opening 3 is a chord of the outside cylindrical periphery, and coacts with the latterto define a narrow externally arcuate face segment of varying width. The width is the greatest at the center and decreases progressively toward opposite ends of each segment 6. The extreme ends of the segments 6 are integrally connected or joined at the corners of the opening 3, thereby producing the grinding element I in one piece entirely closed throughout the external periphery. The connected ends of the seg-v ments 6 also define the narrowest areas 'l of the grinding face 2.

As a result of the foregoing construction, the grinding face 2, about the square center opening 3, has four uniformly spaced areas 6 of relatively large expanse and wide maximum radial dimension, and four connecting areas 'l alternated therewith, and of relatively small expanse and minimum radial dimension. The large areas 6 have a hard cutting action, and are strongly resistant to wear. Conversely, the small narrow areas 1 are comparatively weak, and much less resistant to wear or crumbling. This difference in grinding strength causes the areas l in use to recede from the plane of theareas 6, and thereby impart to the grinding face 2 a slightly undulating surface with four low points and four altervnate high points with highly effective grinding characteristics. Although the grinding face varies in `width and assumes an undulating form in use, it does not have a completely interrupted cutting action, and remains in contact with the work, thereby preventing end play of the supf porting spindle from injuring the work, and instead insuring a smooth flat surface finish on the work.

` The foregoing results are to be contrasted from those obtained in the use of end face grinding vwheels of the type in which a plurality of sepa- 3 ments to break off or disintegrateY excessively, and permits end play in the spindle to mar or impair the work surface, so thata smooth flat work surface is=rrot obtainable:

For optimum. performance.. therati'ot of; the maximum radial dimension, for example through the center of the areas B, to the minimum radiali.` dimension, for example through the narrow confv necting areas 1, should be as large as possibile..

consistent with the strength requiried*tovwiiha` stand centrifugal force, and the permissilolegage,` gregate area of the grindingY faces? fcrafgiveir Y horsepower rating. To this end, thefaream 'l-f preferably are made asi'narrow as is permissible 4within ,the` strength requirements. For a, given di'ametrical', size of WheeL-themaximum radial dimension ofi the face is determined by' the shape and' relative sizeof the center openingf.

If Vthe 'center opening, 3isma'd`etoo smalljjt may. ,l

the corners of the centralopening: In this; event, the. sides 5L-of the opening: 3' are connectedattllelr ends by diagonali corner surfaces Swhicl may be of any desired shape,` and which` in they present' instance are shown as arcuate, and concentric to the. outer peripheral surf-'ac`eli. V AsV a; result, the, connecting areas 'l ofthef'acelietweerr the ends of the segments. 6 consist' of shorti arcuate sections.

The Vabrasive element I` has a., rear. mounting; face 9. adapted to be securedin` position 4against a, 'at. supportingV surface.,l suchv asY the' exposed face of ar circular adapter plate |501, Tot increase*V the. strength cf the abrasive element I particu-- larly at the narrow sections. T, the. rear portion, preferably is formed witha thin annular extendedback Hi which extends. into and underlies the cornerjportionsV of the central opening 3. The

back4 Iii is.. providedo such a width that the sde` surfaces of the opening, 3 are, substantiallytangent to tneinnei: peripheralledge. Ii thereof-. .It will'` be understood that the central opening, 3i extends from the oute'r endfac'e Z'Vinwardl'y, through theelement' Ito the extended hack II.

To further strengthen the abrasive element. I whenA desirable, suitable wi're bands I'may be tightly secured about. thefouter periphery.. i

Within the broad. aspects of the inventiontle abrading` element. I. may he, securedLto' the adapter plate I0, or other suitable. supportin any desi'red, manner.V It. is particularly advantageous, however, to. utilize. awire. anchoringI meansjjmolded directly in the rear portion; andi extended' back I'I of the element I since such means' provides an added reenforcement greatly strengthening the elementlaty thecomparativelynarrow'sections l; and consequently permitting 'the'.latterr to. be made narrower by' vreason of the increased strength than would.. otherwise be permissible. A y suitable wire reenfor'cement may comprise an annular wire mesh I4' molded in the rearportion of the. element I" flush with the rear mounting' surface 91 and' coextensive in sizeI therewith, A'. plurality of Vnuts I iorother screw elements are' also When required,4 the width. ofthe segments 6k may be decreasedto' the desiredmax-f l i'mum dimension by increasing. the chamfer' on 4 molded in the abrasive' element I in position against the inner surface of the wire mesh I4 for attaching the element coincidentally to the backing; platee Nl; In the,presentinstance,` the nuts |52 are? arrangedlin unifbrmiyfperiplrerally spaced relation and centrally between the outer and inner edges of the rear mounting face 9. Any suitable number of nuts I5 may be provided, and, inf chap-resent instance, eight nutsV are indicated,V

ci which. four are' conveniently located centrally of; the segments 6, and the other four are located ati tine abrasive sections 'I within the corners of opening 3. The aggregate thickness of the wire mesh I4 and the superimposed nuts I5 corresponds approximately to that of the extended W sof-thatfall`- cf-tliei abrasive-canbeused down tothebacl; Y j

'For mount: theL abrasive element, bolts I6 are extended'L through openings inthey platevk I-D" and threaded intoy respective nuts Ii- `The mounting' or- :niapterl plate HP in= turn*A is concentrically""bolted to' a colla-rv |58 onf a rotary spindle I9. This' methodoff mounting: the abrasivev element I- hasthe advantagethatV it not onli74 reenf'orces the: element at the wea-l;Y points, but alsoV avoids* the use` of" complicatedY chucks,

flanged' rings' orLV other holding1 devicesV are costly, in construction, andi whichl reduce ftlie amount of' abrasive that can bei wornoff in use.

which is cornn'ron'l'i7h introduced into the# central opening; is' conned'v within the: circular wall of the' opening, andlcan enter thejgrindingzorrelonly with difculty; if? at all', thus tending toresult in unduex heating andy hencew of' ne'cessitylrequiring a slowing; down of;e the, cutting action; Ijrr wheels YYcomprisingindividuali segments; rrruclirY` of' the cooling." medium escapes` and iszl'ostV through the open spaces. between the adjacent; ends ofthe segments; .In contrast, the abrasive elementi I ofY the present invention" confines substanti'ally` all of? the coolant. introduced* into the. central;open-` ing; 3", for effective.' use, Also'. theinoncircular shape ofthe opening 3 tendstc. churn or'jagitate the. coolant andto directritto' the grinding zone. More particularly, the coolant; under the inuenceiof centrifugal force.. tends to fl'ollJ toward and into the corners of. the opening 3;,V Hence, bodies-ofi the coolant are piledljlp' indirect contact with the. surface of the workbetween and in the path of the..abrasiveY segments, V.andare squeezed back; and'` forth .by the advancing segments and VirtuallyA forcedk into grinding zone. Y

It wur be evident, from tneforegoinggthat I have, producedia new and'. improyedmol'd'ed abrasive' grinding wheer or' element with anuninterrupted end facef which will remove' metaglby u grinding; at a greatly increased, rate,'whi'cl"r will end face adapted for grinding, said face consisting of four uniformly peripherally spaced chordal segments integrally joined at their contiguous ends, said element having an inwardly extended baci; at the rear end defining an annular mounting face and underlying the corners of said opening ,which extends thereto, a wire mesh molded in said element adjacent said mounting surface and being coextensive in area therewith, and a plurality of uniformly peripherally spaced screw elements molded in said element against the inner surface of said Wire mesh for securing said element to a rotary support.

y 2. A rotary one-piece dynamically balanced abrading element of bonded abrasive material having a completely closed continuous external cylindrical surface and a central opening extending substantially therethrough from the front end, said opening being substantially square in shape with arcuately chamfered corners and de- .fining a continuous circumferential front endv face adapted for grinding, said face consisting of four uniformly peripherally spaced chordal segments integrally joined at their contiguous ends by narrow arcuate connecting sections, said element having an inwardly extended back at the 'rear end defining an annular mounting face and underlying the corners of said opening adjacent the inner surface of said wire mesh and adapted to receive bolts through the rear end of said element for securing said element to a rotary support, said nuts being respectively located centrally of said segments and at the corners of said opening, and reenforcing bands tightly encircling the outer periphery of said element.

3. A rotary one-piece dynamically balanced abrading element of bonded abrasive material having a completely closed continuous external perimeter and a central opening in the front end, said opening being non-circular and multi-sided in shape and dening a continuous circumferential front end face adapted for grinding, said face consisting of a plurality of uniformly peripherally spaced chordal segments integrally joined at their contiguous ends, said element having an inwardly extended back at the rear end dening an annular mounting face and underlying the corners ofwsaid opening which extends thereto, a wire mesh molded in said element adjacent said mounting surface and being coextensive in area therewith, and a plurality of uniformly peripherally spaced screw elements molded in said element against the inner surface of said wire mesh for securing said element to a rotary support.

LEO F. CARR.

REFERENCES CITED The following references are of record in the iiie of this patent:

UNITED STATES PATENTS Number Name Date 616,160 Sturtevant Dec. 20. 1898 `881,621 Rowland et al. Mar. 10, 1908 51,141,616 Crane June 1, 1915 \;:1;,'I37,245 Johnson Nov. 26, 1929 1,964,537 Shue June 26, 1934 2,082,404 Leshure June 1, 1937 FOREIGN PATENTS Number Country Date 204,533 Great Britain Oct. 4, 1923

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