US 2605592 A
Description (OCR text may contain errors)
CONTACT WHEEL, lMAINLT FOR FTNISHING BELTS l Filed May 10, 1951 2 SHEETS- SHEET 1 'IlIlIII/llllll/11111111111111111111L l l E llllllllll/` ATT'Y Aug- 5, 1952 w. J. cosmos 2,605,592
` CONTACT WHEEL, MAINLY FOR FINISHNG BELTS Filed May 1o, 1951 2 SHEETS- SHEET 2 Y JQ/WMO;
W/LL/AM d. @USA/05 F Dpr Patented ug. 5, 1952 n NLY FOR CONTACT WHEEL, MA1
- Y BELTS A'rEN-'jr'oFFx-cs f FINIsnrNG ,Y WilliamJ,oqsxosfohicagdni. Y y Application Mayf'i'o, 1951, serial No. 225,654`
.. j 2 Claims'.
vThis invention relates to segmental VContact wheels for'abrasivebelts; mainly for service in buiing, burnishing, polishing and other iinishing work; I Y
This application is a continuation inpart of my copending application S. N. 196,916 filed November 21, 1950, now issued as Patent No. 2,581,754, and mainly of the disclosure illustrated in Figures 17 to 19 of that application. The invention provides an improved molded disc unit for contact wheels ofthe type as indicated.
`The art is familiar with the use of pleated or ruiiied cloth, laminated 'to form buffing wheel discs Which are directly covered with abrasive material. The art also knows-bung wheel or grindingwheel discs similarly covered but molded with radial' 'corrugations nested together to`-form a solid `working surface. For instance this is shown in A. J .'Doermanns Patent No. 1,912,069. Such a rworking surface of a buiing or grinding wheel has theadvantage that it prevents the marking of the workpiece. Marking occurs when abrasiveparticles are embedded in the rim of a segmental grinding'or buing Wheel at ornea'r a joint between segments and if the joint extends in the plane of rotation of the Wheel.
It has occurred to me that a somewhat similar' 'problem of contact Wheels'for abrasive belts can Aabrasive belt in a manner which prevents marking of the work piece; it also adds materially to the effective life of the belt, and itk facilitates the adjustment of amounts of material removed from the work piece, and the selection of abrasive belts ,suitable for dierenttypes of work.
y All this will be understood more clearly upon consideration of the detailed description which follows.` In the drawing appended hereto, Figure 1 Yis a perspective diagram of a contact wheel according to this invention. Figure 2 is a sideview` o f this'wheel. Figure 3 is an enlarged, crossfsectional elevation of a disc unit or segment according to this invention, diagrammatcally indicating its mounting and assembly. Figure 4 is'an endview of this segment. Figure 5 is a more enlarged,partial 'endview 'of the Wheel. Figures to Figure 5. f
A belt A, coated with relatively fine abrasive granules, is driven injdirection B by the contact wheel or actuating vdevice C, composed of generally disc-shaped segments D. Each segment has a relatively flexible rim E consisting in generally fan-shaped foldsv or corrugations. In the central part of the contact wheel there is a central, circular opening F for the drive shaft Grpreferably with a bushing H interposed. The contact wheel is secured to the 'drive shaft by a nut J, engaging screw threads K on one end 0f the shaft and pressing the contact'wheel against a shoulder L on the shaft oppositethe screw threads. Washers.
or end plates M maybe interposed between the contact wheel and the shoulder, and between the contact wheel and the nut;
The discs `D of the rcontact wheel C are lined up axially on the bushing H. Their hub portions are in direct contact With one another and pressed together by nut J and shoulder L. They may also be permanently bonded together, for instance by cementing, so that they -Will not come apart even when the nut, J `is loosened to remove'the wheel from the shaft.
The body and mainly the rim portion ofv each disc D is preferably molded of a plastic material such as soft rubber. i This insures positive traction on the abrasive belt A` and .resilient exure of this belt at the point'of contact with the work piece P. Each disc D is positively centered on the bushing H by a relatively rigid, preferably metallic, circular insert plate Q, which is molded into and substantially covered by the rubber body. Ths serves also as a reenforcement forthe disc,which preventsor contributes to prevent undue expansion of the disc upon high-speed rotation. Such expansion can be additionallyprevented by suitable side reenforcements for the disc, made of textile fabric or the like.
The thickness T of the inner or hub portion of each disc D is greater than the width of the outer or rim portions of the disc, but smaller than the amplitude S of the corrugations E formed by said rim portions. As a result, when the hub portions of any two discs D are in contact with one another, the rim portions of the two discs are spaced by slight, but positive distances u.
The fan-shaped corrugations E are formed by molding the rim portion of the disc in form of folds; each fold preferably extending in a radial direction with respect to the center of the disc. The contact wheel can then be dressed repeatedly when its surface has been worn or unbal- 3 anced by continued use. Such repeated dressing is facilitated by the feature that the reenforcements Q of the discs are covered by and smaller than the discs themselves.
In Figure 5 the folds or corrugations E comprise alternating strips I extending in a diagonal direction across the face of the disc and wheel; intermediate strips II extending in the opposite diagonal direction; and joints I2 between these strips at their lateral ends; the strips I0, II and joints I2 being elongated and radially disposed as mentioned. The form of the different strips I0, II is identical as to their width t, angularity :c and other features of configuration;l this is important mainly if it is intended occasionally to reverse the direction of rotation of the contact wheel.
The amplitude or width S of the corrugations E exceeds the thickness T of the discs approximately by twice the width t of the strips I0, II, whereby the joints I2 of each dise are located adjacent to but substantially outside the planes y of the sides of the disc. A greater overhang of the joints I2, beyond the sides y would result in a flexibility of the strips which is greater adjacent their ends than in the middle. This' in turn would result in unequal actuation of the belt. and improper abrasion of the work piece.
In order to avoid such inequality it is desirable noto'nly tc keep the joints I2 adjacentY the sides y but also to make the joints I2 somewhat stronger than the body of each strip I0, I I. To some extent such strengthening is-inherent in the Z-pattern design. Further, the inside corners I3 between the strips may be rounded off more than the outside edges I4 Yof'the joints I2. The effective hardness of the working area l5 can be made substantially uniform, across the face of the contact wheel, by the exp'edients mentioned.
At'the same time the strips or folds` Iii,` II form a continuous zig zag or Z-patterned stripe in each working area I5. They are separatedby distances u, whereby each fold can flex indi.- vidually Without substantial interference by other folds. This feature is obtained without any expensive and wasteful cuttingv operation on the outer surface of the contact'wheel. Itresults` in a particularly efficient operation of the abrasive belt'.
In this operation the contact wheel' CA rotates rapidly, whereby its flexible; corrugatedirim portion expands centrifugally to somefextent. Thesurface of the wheel is dressed so that it has the necessary flat or special contour at the prede-V termined speed of rotation. The rotating wheel grips the inside of the abrasive belt A and movesthe belt at the predetermined speed. against the resistance of the work piece P. As this workpiece is pressed against the belt the abrasive particles remove minute chips of material from the surface of the work piece, and the contactv wheelfi'slocally distorted.
It is this distortion of the contact/wheel and the related operation of the abrasive beltV which They remove a greatv number ofsrnallrparticlesv from the surface of the workpiece. Therefore they tend to fill or load the interstices rapidly. This tendency leads to the rapid arrival of inoperability or burning of an abrasive belt.
This burning tendency is strongly counteracted by the special flexing of the belt as described, and the effective life of finishing belts is greatly extended in this manner. I have obtained, for instance, an effective life' of 24 contact minutes when testing a contact wheel generally similar to that described above, with an abrasive belt of paper, commercially known as 14ft. x 4 inch No. 80 ALO-EC-M belt. The test was made on a work piece of low-carbon descaled steel of the grade known as 1015T. The speed was 7350 surface feet per minute. This effective life is materially longer than that which canbeobtained with the best applicable contact wheels previously known, under comparable conditions mainly as to the finishing belt, the work piece and vthe voperating speed. The contact wheelfusedin the test was Vmerely-experimental; the effective life ofthe belt can belengthened further, by changes applied to the new contact wheel C in a manner which is obvious in view of the present disclosure.
Effective life is one ofthe most important considerations in the application of. finishing belts. However, it may be also important to remove some definite amountsof material from the. surface of the work piece. An increase in the amount'of material removed during each contact minute'can be `obtained for instance by using the modified working surface of Figure 6. This'increase isY usually obtained at the cost of a certain reduction ofthe effective life of the belt.
In` this modified form the distances between the strips'IO are greater than thedistances between the intermediate strips lil.. This can be achieved very simply by a modified assembly and bonding together of identicall discs C. The closely adjoining or abutting stripsll are less free to' flex than are the strips Ill.` Solidv or semi-solid land areas -areformed in this. manner. The rangeY of flexing. operationsin the-belt isk decreased.
Another modifiedv assembly is used in Figure '7. Here afurther increase in materialr removed' per contact minuteis .obtained by incorporating serrations I6 in, the contact wheel' C. In the form ask shown, the working surface is interrupted by eliminating the strips I0 in their entirety. In thisv manner the strips Il are isolated so that they form, projecting teeth of a` serrated pattern. The different teethror stripsV II are lined up to form diagonal land or working areas I'I extending helically'j, across Vthe face of thev wheel. The rem-oval of the strips Il) can beachieved by molding or cutting or otherwise. The serrated pattern can be rel-established for instance b-y re, dressing the surfaces I1 and' cutting av deeper groove-I8 uinto t-he'face of the contact wheel between theseV surfaces.
In comparison with theV` finislfiingA contact wheel of Figure 5 that of Figure Gis more aggressive and that of' Figure 7 is much more ag'gressiverf The contact wheels ofliguresv 6 and 'Tinay best-be operated with relatively coarse belts, in comparison with those for Figure 5. lIn this-manner the amountv of materia-l removed is increased and-a `more adequate effective life of the-.beltis obtained-v the operation is more-of ithe .burnishing,v grinding orl stockv removing" ype.4
canbe made asne and mild asis possible by-anyf On. the other handthe operation of acontactwheel and abrasive Abeltlin. accordance herewith" other tools presently available. Figure 8 shows a further modication of the fan-shaped disc which is useful in this respect. Here the corrugations of the rim are wavy rather than sharpcornered, thereby providing curved or bent portions l9 between the strips I0, Il. The inner and outer curvature 20 of these bent portions I9 may have similar radii, of substantial length in comparison with the width of the disc D. The resulting, wave-patterned working areas 2| have substantially uniform width throughout their length, thereby eliminating the corner joints and reenforcements l2 and enabling all parts of the corrugations to bend still more freely in all directions. The flexibility and belt-cushioning effect of the working" areas 2|.can 'be kept uniform along this working area 2|,l if the wavy folds are long enough, in directions radially of the contact wheel, to eliminate the inequality due to the overhang of the bent portions I9.
The contact wheel of Figure 8 is generally the most yielding one of the different types illustrated. It is comparable, in this respect, with a soft cloth buing wheel. It can best be used for fine polishing, and for the finishing of sharply curved surfaces. The wheel of Figure 5 is somewhat less yielding and is suitable for work with stronger abrasive belts. The wheel of Figure 6 is still less yielding and is suitable for considerably rougher belts. The wheel of Figure 7 is yielding in manners more similar to those of standard serrated contact wheels. It is suitable for rather aggressive and continued stock removal.
The wheels of Figures 5, 6 and 7 can be made with identical mold equipment. Similar variations of course can be obtained with the wheel of Figure 18.
The grinding wheel according to said Doermann patent can probably be considered as the closest approach of the prior art to the present type of wheels. It is constructed with a solid working surface and with a practically uninterrupted coat of abrasives thereon, whereby it is made unsuitable for use as a contact wheel. If the direct coating were removed, and the wheel used to actuate an abrasive belt it would act substantially like a plain, unpatterned, unserrated contact wheel. Mainly when used with a finishing belt it would burn the belt rapidly, in comparison with any of the present wheels. On the other hand, when used with a coarse belt it would not remove stock nearly as rapidly as does, for instance, the present wheel of Figure 7. Even when serrated with grooves or similar contour, it would operate diierently.
Persons skilled in the artV will be able,'upon consideration of this disclosure, to produce further lmodifications, within the spirit of my invention. I claim:
1. A contact wheel segment consisting in a generally disc-shaped body, the peripheral part of which is elastic and slightly expandable centrifugally and shaped in form of radially eX- tending corrugations, while the central part of the body is thicker than the peripheral part thereof but thinner than the width of the space occupied by the corrugations and comprises rigid, disc-shaped plate means coaxial with and rmly bonded to the body, so that a contact wheel formed of several such segments axially aligned with their central parts in mutual contact and with the corrugations nested together has a body reenforced against excessive centrifugal expansion, and a working surface consisting in stripes which have a corrugated outline and are spaced from one another.
2. A contact wheel. according to claim 1, wherein the peripheral part is substantially composed of soft rubber and the rigid plate means is substantially composed of metal.
WILLIAM J. COSMOS.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS Number Y Name Date 1,841,411 Kux Jan. 19, 1932 2,109,905 Lipitt Mar. 1, 1938 2,198,282 Hall Apr. 23, 1940 2,378,643 Losey June 19, 1945 2,527,554 Kimball Oct. 31, '1950 2,530,960 Hall Nov. 21, 1950