US2581754A - Contact wheel section - Google Patents

Description

1952 w. J. cosmos CONTACT WHEEL SECTION 2 SHEETSShEET 1 Filed Nov. 21, 1950 JNVENTOR. il YZZJAM J 006%06 F. v r

arm/ME) Jan. 1952 w, cosmos 2,581,754

CONTACT WHEEL SECTION Filed Nov. 21, 1950 2 SHEETS-SHEET 2 IN V EN TOR. W ZLMM J 006 /1/06 Y D- d HTTOR/VEY Patented Jan. 8, 1952 UNITED STATES PATENT OFFICE 2,581,754 CONTACT WHEEL SECTION William J. Cosmos, Chicago, Ill.

Application November 21, 1950, Serial No. 196,916

Claims. 1

This invention relates to high-speed contact wheels for polishing, grinding and similar purposes, and particularly to a high-speed contact wheel unit or so-called section of annular disc form, forming a new article of commerce. A plurality of the annular disc units can be combined, forming thereby a high-speed segmental contact wheel which is more suitable for several of its purposes, and at the same time more economical than are the earlier contact wheels.

The units consist mainly of elastic annular disc with ribs on their sides. Preferably each unit consists of one elastic, annular ribbed rubber disc, permanently bonded to one or more rigid, annular flat disc means to insure safe and dynamically balanced operation at high speed rotation. A contact wheel is formed of such units separably sandwiched together. The ribs of the units preferably act as reenforced serrations on the wheel.

The advantages of such ribs, of the reenforced serrations, and of other features will best be explained in connection with the detailed description which follows. In the drawing:

Figure 1 is a schematic substantially isometric front view of a contact wheel in accordance with this invention, also showing an abrasive band driven thereby, and a part which is being worked upon:

Figure 2 i a schematic axial section through such a wheel.

Figure 3 shows one of the annular disc units of such a wheel in a view similar to that of Figure 2 but enlarged in scale.

Figure 4 is a partial side view of such a disc.

Figure 5 is a partial front view of a wheel composed of such discs.

Figures 6, 7 and 8 show a modified embodiment in views similar, respectively, to Figures 3, 4 and 5.

Figures 9, 10 and 11 show another modification in similar views, respectively.

Figures 12 and 13 show a third modification in views similar, respectively," to Figures '3 and 4.

Referring first to Figures 1 to 5:

The segmental contact wheel W, substantially composed of annular discs or slabs or contact wheel sections S, drives an abrasive belt A to work upon a part P. A suitable number of annular discs S are usually combined into a wheel W to substantially match the width of the part P, and of course a belt A of suitable type and width is employed. It is well known to the art that the rotating wheel, slightly expanded by centrifugal force, grips the inside of the belt and moves in the direction shown by the arrow in Figure 1,

and that the rotating contact wheel through the moving belt acts as a resilient abutment for the work piece P; this basic operation serving to minimize the tension absorbed by the belt and to prolong the useful efiect of the abrasive coating on the belt.

In order to form a wheel W having suitable width, and at the same time to allow rapid and efficient rotation of the wheel, as desired with modern abrasive bands, the annular discs S are preferably interchangeable, adapted to laterally engage one another by special ribs, centrally rigid, peripherally somewhat expandable and preferably surface-patterned as required in each application. This combination of basic features is believed to be new. Interchangeable discs or slabs are known in cloth wheels and the like; however, the present contact wheel has an improved surface pattern and expansion controlling structure, not previously used either in contact wheels or in cloth wheels or the like.

The new discs are combined into a solid contact wheel by aligning them on a drive unit such as shaft D and holding them in place, for instance by providing nuts N engaging threads on the shaft. In order to keep the end surfaces of the wheel smooth I may cover them with fiat rubber discs or rings R axially aligned with the slabs S. g

Contact wheels of the type contemplated are usually rotated at high surface velocities, such as 10,000 feet per minute, and are therefore subject to high centrifugal forces. The forces are allowed to expand the elastic rim of the wheel to a certain extent, providing a yieldable abrasive belt surface as generally indicated in Figure 1.

Such expansion and yielding are strictly controlled for each application of the present apparatus. In particular the centrifugal force is counteracted to protect the wheel and any adjacent personnel and property from injury, and also to protect the wheel and connected machinery from objectionable vibration, dynamic unbalance, noise, chattering and the like. Provision is also made to avoid objectionable relative shifting of annular discs, even in the event that the contact wheel operates with a high power output for heavy stock removal.

For these purposes each annular disc section S consists of an elastic annular disc 20 of suitable density, axially aligned with and firmly vulcanized to a smaller, thinner, more rigid, flat annular disc insert plate 2!, preferably of aluminu'rh sheeting. In order to provide a good bond between the metal and the rubber I prefer making the side surfaces of the metal disc rough, for instance by coarse sandblasting.

The two disc elements and the entire disc unit are annular, having central shaft holes 22 of uniform diameter to fit the drive unit D. A plurality of annular discs S can thus be assembled on a drive shaft D, in accurately coaxial alignment, regardless of the exact pressure pattern set up in the rubber discs 20 by the tightening of nuts N. Such alignment is also preserved when the wheel is rotated at high velocity and still further when it is disassembled and reassembled with equal or different numbers of slabs. Thus the annular discs S are freely interchangeable to form contact wheels of suitable width.

The surface pattern The rim of each annular disc, that is, the elastic outer portion of the rubber disc 20 not restrained by the aluminum disc 2|, has uniform, elongated, solid, semicylindrical ribs 23 formed on its; sides and integrally molded therewith; the sidesotherwise being flatand parallelwith; one another, but the ribs projecting laterally beyond the flat planes of the sides by substantial dis,- tances, as best shown in Figure 3. The ribs 23 on one side of each rubber disc are preferably stageered with respect to those on the other side by uniform distances. Therefore, as shown 'most clearlyin Figure 5 the peripheral end surfaces of these ribs provide a surface pattern on the contact wheel, comprising relatively rigid, solid rounded dots formed by the ends of the ribs 23. The" dots are slightly elongated transversely of the disc unit. and extend obliquely with respect to the sides of the disc unit, in areas 2i alternating with more flexible intermediate areas 25. Preferably such areas 24, 25 form parallel stripes across the peripheral cylindrical rim surface of the wheel, at an angle-with the peripheral edges, whereby they resemble serrations of certain earlier contact wheels. However it is also possible, in some cases, to form an irregular pattern of such ribs.

It is known to the art that suitable surface serrations and the like, on a contact'wheel, will improve the abrasive action of the band greatly.

.Depending on the type of work to be done, suitable dimensions can be adopted for the width, depth and angularity of the slots and intermediate flats forming the serrations. Together with a suitable density of the surface material, a suitable surface speed, and of course suitable abrasive material, the so-dimensioned serrations will produce optimum conditions for each type of grinding, polishing or other work.

. These desirable conditions, heretofore attained transverse bridges 26 act as reenforcements or abutments for the areas, 24. It seems to nae-although I do not wish to be limited by the theory stated-that they cushion the impacts which oc cur directly or indirectly, between the areas 24 and. the work piece I, as the wheel rotates. In actual; practice I have found that such spaced reenforcements 26 arev extremely useful, main-- ly in counteracting mineral-shedding surfacescratching and chattering operation. Even with flexible areas 25 of considerable width, the operation can be both rapid and aggressive by means of such reenforcements.

This combination of operating features is very useful. Heretofore, when a contact wheel was intended to operate somewhat aggressively, for heavy stock removal, it was generally necessary to use relatively narrow slots however, this in turn was apt to cause loading or glazing of the abrasive surface with material removed from the work piece. Substantially 7 better utilization of the abrasive surface is provided by the reenforced serration pattern as shown, with fairly wide flexible areas-25. This applies mainly at high speeds, but thesame pattern is also useful for relatively low surface speeds such as 7500 feet per minute. In other words, it also enlarges the scope of application of a given surface pattern, and reduces the need of change-overs.

It will be understood that the detailed spacing and other dimensioning of the, bridgeszfi and of the other parts of the surface pattern is a matter.

of choice and design, for each individual typeof contact wheel. However, caution must be exercisedsincethe material forming a bridge 26;.may tend to act somewhat like a flat or solid area 24, if the bridges 28 are wide in comparison with the remainder of theslot areas 25; that is, if the ribs 23 are narrow in comparison with their discs 29. Therefore I generally prefer ribs 23 of rather substantial width, and relatively slender discsZU, thereby also reducing the materialcost and fur ther improving the high-speed operation bya reduction of mass and vibration. l r

A surface pattern with reenforced serrations can be impressed on a conventional,non-segmene tal contact wheel. However, the present I segmental wheel provides this desirable pattern at lessgexpense and greater efficiency. One important reason is that the ribs for the present annular disc construction can be produced in a few sets of simple, economical molds-one for ,each wheel diameter, more or less independently of the width of the wheels formed from the slabs or disc units. On a non-segmental wheel reenforced serrations like those of Figure 5 can be produced only by providing core-molds in much greater number-at least one for each diameter and width of a wheel; also in more expensive form-suitable for the; molding and curing of greater masses of rubber.

It is usually desirable to form and maintain a regular wheel surface pattern without breaks, bends Or the like in the areas .24. For instance it would be undesirable in the pattern; according to Figure 5' if some of the right hand discs were shifted downwards with respect to the left hand discs. This would lead to a relative concentration of average density or rigidity in the middle of the abrasive surface. Asa result, shadow marks or the like would often appear, .mainly when the wheel is used for polishing purposes.

It is therefore necessary to form. the surface pattern accurately and to maintain it safely, for instance against shifting tendencies occasioned by unavoidable irregularities in work pres sure. Therefore III prefer making sucessive annular discs self-positioning as to angular alignment;

a feature which also allows the use of smaller V and more economical fastening means N; One simple method of making the disc units substantially self-positioning is based on the arrange I5 ment diagrammatically shown in Figures 4 and'5.

-At the inner ends of the ribs 23, adjacent the periphery of the aluminum disc insert 2|, the ribs of each disc unit have distance from one another which is approximately equal to and as shown, slightly greater than the width'of such ribs; the width being uniform throughout. This facilitates the original assembly of a segmental contact wheel, and also aids in maintaining the original assembly pattern.

Afurther aid in the latter respect is provided by a rough outside surface of each disc. I provide such a rough outside surface by vulcanizing a suitable reenforcement 21 to each side of a slab S. 1-

Reenforcements In their preferred form such side reenforcements 2'! are annular discs of fabric, coaxial with and of larger diameter than the metal disc insert 2|. They may consist of material similar to that of disc insert 2!; in fact they may replace that disc insert. Preferably, however, they consist of a fibrous fabric such as coarse cotton duck material; In either event the outside reenforcements 2'! will not only serve to hold the wheel together, against shifting tendencies, but will also serve to hold each annular slab together,

against deformation and possible disruption due to centrifugal action. I e

. It is often best to locate and utilize fabric side reenforcements 21 mainly peripherally, as reenforcements against excessive peripheral expansion of the rubber disc 26, and to locate and utilize a solid metal reenforcement or hub insert 2! mainly centrally, as 'reenforcement against irregular transmission of force and movement from the drive unit D to the slab S. However, as indicated, each reenforcement 2 l, 27 can serve all these purposes; and thus it may be best to make the side reenforcements 21 annular withan inner periphery similar to that of parts 20, 21.

Manufacture and maintenance The process of making a contact wheel disc S, in accordance herewith, is extremely simple. Heretofore it was usual and necessary to use foundry forms for metal hubs and mold forms for the rubber rim; to machine the castings for static balance, and the rubber rim for serrations, and to perform a number of other costly operations. A distinct saving is provided, by the segmental hub formed by a number of flat reenforcing plates 2| which can be accurately punched out of metal sheeting or the like, withrelatively low tool and fabricating costs. These reenforcing plates, properly punched, are assembled on a mandrel in the mold for the rubber or other elastic disc 20 to be sandwiched therewith. No machining of the molded disc is usually required, prior to the assembly on shaft D and the dressing of the peripheral wheel surface.

In operation the present contact wheel usually runs at a surface speed of about 5000 to 15000 feet per minute. Each rubber disc 20 expands centrifugally due to such velocity; more so in the layers remote from the reenforcing disc means 2!, 2.1 than in their direct vicinity. Initially, the wheel is dressed so that it may exhibit the proper contour-usually flat-at. the intended speed. It has therefore, a slightly irregular contour when at rest or when rotating at substantially less than the intended speed. When running atproper speed the wheel moves the abrasive grit over the work piece with maximum efliciency. The front edge of each effective serration 24 acts likea file;

the application of such files being"-moie"gradual and less hammer-like than heretofore, due to the reenforcing bridges 26.

When it has been used for some time, th wheel usually is dressed again, at which time new portions of the ribs or reenforced serrations are brought to the surface. For this purpose the ribs, as best shown in Figure. 4, extend from the periphery inwards toward the central part of the disc. After a number of dressing operations, when the elastic body and ribs have been used up the remaining, inexpensive reenforcements and the rubber vulcanized thereto can often be discarded. I

Modified forms:

The embodiment of Figures 6, 7 and 8- is modifled in several respects. Here the elastic disc 60 has ribs 63 with cornered cross-sections aiding in strong, aggressive stock removal. For the same purpose I may recess the peripheral disc surface in the more elastic regions, forming slots 65 between the solid regions and thereby also promoting the formation of cooling air currents '68.

I have already mentioned that in order to keep the overall weight of the annular disc as low as possible and thus to save cost and minimize vibration, I may reenforce the elastic disc merely by a single insert 61 of some suitable perforated material or fabric; that is, I may eliminate side reenforcements as distinguished from the side ribs, which I retain. However, I usually retain at least a pair of central washers M, which are preferably secured to the disc unit, in order to insure accurate centering of each unit on the disc shaft. The side surfaces of the washers are preferably roughened, for purposes explained above.

The embodiment of Figures 9, 1-0 and 11 is still lighter. Here the elastic annulardisc has a relatively large'inside diameter and the reenforcing insert 91 is substantially uncovered by rubber between this annular disc and the central washers 9|. It will'be understood that such reenforcement may be'foraminous or solid. It may consist of fibrous fabric or metal screen material, metal sheet material, relatively hard rubber, plastic, or partly the one and partly the other. Specifically, the insert material 91-A embedded in the elastic disc 20 may be madeof some fabric which has approximately the same density as does the disc 20, and which can be trimmed together with the elastic material when the wheel surface is dressed at and for the intended rotational speed. Inner parts 97-B of the insert or reinforcing material can be selected exclusively for resistance to the centrifugal forces encountered at capacity speed, and to the torsional and bending forces encountered at lower speed or at rest.

At the high speeds contemplated herein,it may be desirable to keep the width of the relatively flexible areas between the ribs 93 (see Figure 11) uniform, even if and when the wheel is dressed down to smaller size after continued heavy service. Therefore the ribs. 93, as best shown in Figure 10, may have outwardlyincreasing width, and may confine laterally recessed spaces or slots 95B therebetween, which spaces are bounded by parallel edges along the side surfaces of the elastic disc. Of course it is also possible to increase the width of both elements-ribs and intermediate recessesin outward direction.

Cooling air currents can beestablished and promoted even if the reenforcing bridges 95, across thefiexible-areas 95, are not recessed on 7. their surfaces. As shown in Figure these bridges may beperforated by orifice holes 95A for this purpose. Somewhat similar holes have previously been used in certain contact wheels, for basically different purposes. 7

The ribs according to Figure l0'may best be combined with a self-positioning pattern slightly different from that in Figure 4. As shown'in Figure 11, the slab has recessed surfaces 98 on one side and correspondingly protruding surfaces 99 on the other side of each elastic disc and rib thereon. This arrangement is further useful when the 'areas 95 are wide; that is, when the wheel isintended for work on soft materials,

which tend to glaze or load an abrasive belt if the slots are narrow. p The light disc units of Figures 6 to if are mainly intended for applications where centrifugal forces. are kept in relatively moderate limits; Another light slab is shown in Figures 12, 13; it is. mainlyintended for applications where the operating speed must be very high, the wear and tear on the slab is heavy, dressing of wheel sur faces must be frequent, and therefore a considerable mass of elastic rim material is provided initially, leading to a high centrifugal force;

Such material must be anchored safely against forces tending to expand it irregularly and to cause vibration, chatter, or disruption. Therefore, I provide the annular elastic disc [200 not only with one or several reenforcing inserts I291 but also with metallic side reenforcements [20L vulcanized to the disc and additionally anchored thereto'by buttons i220 integral with the elastic disc material. choring buttons in the rim, I punch a series of peripheral holes I221 into the metal side plates [20L I can do this in the same operation in which the central shaft hole I202 is formed. Theanchoring buttons will then be formed automatically when the slab is molded.

only to counteract it, I make the elastic rim I200 just as thin, in a radial direction, as may be possible when providing suflicient stock for one or several dressing operations, and some times for extra anchorage. by integral buttons or the like. For this purpose I may install a metal ring or hub i222 between side plates 820i, concentric therewith. This construction is contemplated mainly for contact wheel slabs of relatively large diameters.

Another expedient to reduce or vary the centrifugal force involves the provision of ribs I203, on the sides of the elastic disc, which run at fairly large acute angles with respect to the radii, with the same inclination throughout on both sides ofthe disc. The mass or weight of material contained in such ribs is the same as in radial ribs, so long as the width of surface flats, thickness of rim'material and disc diameter are the same; however, when rotating the wheel in the proper direction, counter-clockwise in Figure 13, the outward moment of the centrifugal force with respect to the peripheral layer of material is reduced, leading to better distribution of elastic stresses, less vibration in the wheel, and less ex; pansion. At other times it may be preferred torun this wheel clockwise in order to expand it substantially and thereby to hold on it, for instance, a separable, circular abrasive band (not shown). 7

Still other modifications are possible. For instance, instead of plainrubber I may utilize other elastic materials, for thecorrugated disc, and I In order to incorporate such anmay use such materials in a wide. range of densities, for different types of work. Instead of aluminum or fibrous fabrics or both I ma use other reenforcing materials, including relatively hard rubber and other plastics. Persons skilled in the art will be able to conceive further modifications, upon consideration of this disclosure.

I claim:

1. A generally disc-shaped section for contact wheels and rolls, having a generally central, rigid part and a generally peripheral, elastic part; the central part comprising a rigid hub and an elastic body bonded to the hub and to the peripheral part and having generally fiat, parallel sides; and the peripheral part comprising an elastic body with generally flat, parallel sides and on each of said sides, a series of substantially uniform and radial ribs, each rib extending from the periphery'of the peripheral part inwardly along the side to an area adjacent the periphery of the central part, the ribs of each side being distributed over the entire peripheralpart and spaced apart by substantially uniform peripheral distances greator than the width of each rib, and the bodies of the ribs being solid, at least approximately semi cylindrical, and wide enough to project laterally beyond the sides of the central and peripheral parts by major distances in comparison with the width of the body of the outer part, so that a contact wheel formed of such sections in direct contact with one another has a working surface formed by peripherally and laterally distributed, laterally overlapping and peripherally spaced end surfaces of the ribs and by narrow bridges formed by portions peripherally interconnecting said ribs".

2. A section according to claim 1, wherein the minimum spacing of the ribs, adjacent the periphery of the central part, is only slightly greater than the width of a rib, so that a regular pattern of rib end surfaces is formed and maintained on the working surface of a contact wheel formed of such sections in direct contact with one an other, by the mutual engagement of the inner ends of the laterally projecting ribs.

3. A section accordingto claim 1, wherein the ribs on one side of the peripheral part are stag gered with respect to those on the other side, so that each rib end surface on the working surface is slightly elongated transversely of the intercomnecting bridge and extends obliquely with respect thereto.

4. A generally disc-shaped section for contact wheels and rolls having a large generally central. rigid part and a narrow, generally peripheral, elastic part; the central part comprising a large, rigid disc to provide a hub and reenforcemerit and an elastic body laterally bonded to the rigid disc and to the peripheral part and having generally flat, parallel sides; and the peripheral part comprising on each side thereof, a series of substantially uniform ribs, each rib extending in a substantially radial direction from the periphery of the peripheral part inwards along the side to an area adjacent the periphery of the central part, the. ribs of each side being distributed over the entire peripheral part, and the body of each rib projecting laterallybeyond the plane of the respective side of the central part, so that, when the section is rotated rapidly, the resulting centrifugal forces acting upon the ribs and body of the narrow, peripheral, elastic part are substantially absorbed adjacent the working surface around the entire section, thereby keeping the working surface substantially free from dynamic distortion.

9 5. A section according to claim 4, wherein the rigid disc is disposed between the sides of the central part, and which comprises additionally a fabric reenforcement sheet bonded to each side and extending from the central part to adjacent the periphery of the peripheral part.

WILLIAM J. COSMOS.

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

UNITED STATES PATENTS Number Name Date 254,811 Flagg Mar. 14, 1882 257,308 Flagg May 2, 1882 875,935 Landis Jan. 7, 1908 1,213,051 Wickes Jan. 16, 1917 1,386,722 Mather Aug. 9, 1921 1,459,509 Knothe June 19, 1923 1,685,538 Glidden et al Sept. 25, 1928 Number Number 20 622,887

10 Name Date Semon Apr. 28, 1931 Doermann May 30, 1933 Hall Oct. 5, 1937 Kreilick et a1 Jan. 25, 1938 Lippitt Mar. 1, 1938 Herchenrider June 13, 1939 Hague Aug. 8, 1939 Hall Apr. 23, 1940 Losey June 19, 1945 Fowler June 18, 1946 Hall Mar. 18, 1947 Dodge Mar. 23, 1948 Kummer Aug. 23, 1949 Kimball Oct. 31, 1950 Hall Nov. 21, 1950 FOREIGN PATENTS Country Date Great Britain May 9, 1949

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