US 3553906 A
Description (OCR text may contain errors)
Jan. 12, 1971 w s w 3,553,906
DUAL-ACT ION ABRADING TOOL Filed Nov. 29, 1968 INVliNlUR.
Mew; ///A/5#4// wmamazh, -e/ M M United States PatentOffice DUAL-ACTION ABRADING TOOL Meral W. Hinshaw, Inglewood, Calif., assignor to Diamond Tool Associates, Hawthorne, Calif., a corporation of California Filed Nov. 29, 1968, Ser. No. 779,830
Int. Cl. B24d 7/18 U.S. Cl. 51-209 6 Claims ABSTRACT OF THE DISCLOSURE An abrading machine having a rotary head carried on a vertical spindle on a movable supporting arm, the head having a coaxial tool ring formed in sections and carrying abrading elements in the form of layers of diamond, and also having a counter-balanced and similarly formed eccentric ring disposed inside the coaxial ring and extending from one inside edge of the latter beyond the axis of rotation.
BACKGROUND OF THE INVENTION This invention relates to rotary abrading tools of the type having a head with a generally flat surface carrying abrading elements for finishing engagement with a generally flat Work surface during rotation of the head, and relates more particularly to a tool in which the abrading elements are carried on a ring fastened to the head.
' For polishing materials such as slabs of marble, terrazo or granite, one type of head uses a ring with elongated bars or strips of abrasive material in the form of diamond particles and bonding material applied as a thin layer of appropriate shape, the ring being coaxial with the head .so that the abrasive elements revolve along a circular path as the head is guided along the surface to be finished. SUMMARY OF THE INVENTION The general object of the present invention is to provide an improved tool of the foregoing character which has a more effective abrading action making it possible to finish a surface more rapidly, and also having less tend- 1 ency to walk along the work surface. as a result of the reaction of the elements with the work. More specifically, the invention resides in a novel tool in which a second abrading ring is eccentrically fastened to the head to cooperate with the first ring in providing a dual abrading action that is suprisingly more effective and rapid in removing stock and that stabilizes the head during operation to simplify the problems of control and positioning by the operator. In the preferred form, the eccentric ring is within the coaxial ring and extends from one side of the latter at least around the axis of the head.
Other objects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary perspective view of part of a finishing machine equipped with a head embodying the novel features of the present invention, and showing the head in operation on a slab being finished.
FIG. 2 is an enlarged view of the underside of the head, taken along the line 2*2 of FIG. 1 with the head stationary.
FIG. 3 is an enlarged fragmentary cross-section taken along the line 3-3 of FIG. 2.
FIG. 4 is an enlarged fragmentary cross-section taken along the line 44 of FIG. 2.
DETAILED DESCRIPTION As shown in the drawings for purposes of illustrattion, the invention is embodied in a rotary abrading tool of the type used for polishing of a masonry slab 11 such as marble or granite with a machine 12 including a polishing head mounted on a spindle 13 journaled on the end of a movable vertical axis 15 by belts 17 trained around pulleys 18 on the spindle and driven by a suitable power actuator (not'shown). Control switches are provided at 19 on the end of the arm, and a hoop-shaped handle 20 projects outwardly from supporting elements 21 and 22 on the arm to the grasped by an operator who manually guides the tool along the work surface 11 with the handle.
The rotary head of the machine is in the form of a disk 23 centrally secured to the lower end of the spindle 13 and having an upstanding peripheral flange 24 forming a recessed upper side 25. On the underside 27 of the disk is a tool ring 28 comprising a plurality of arcuate sections fastened to the disk in closely spaced relation by bolts 29 inserted through the disk and threaded into the ring sections, and carrying a circular series of abrading elements 30 in the form of elongated bars or strips of abrading material bonded to the fiat underside of the ring. In a diamond tool, these bars are thin layers of diamond particles and bonding material, as shown slightly exaggerated in FIG. 3.
Preferably, the outer edge 31 of the ring 28 is flush with the outer edge 32 of the disk 23, as shown in FIG. 3, and the diamond elements 30 are elongated and inclined across the radii of the disk with the inner ends in advance of the outer ends as the tool is rotated in the direction indicated by the arrows in FIGS. 1 and 2. Thus, the abrading elements revolve along a circular path about the axis 15, which is moved over along the surface to be polished so that all of the surface is abraded and finished.
In accordance with the present invention, a second tool ring 33 is mounted eccentrically on the underside of the disk 23 and is provided with abrading elements 34 similar to, and coplanar with, the elements 30 to rotate eccentrically about the axis 15. Specifically, the eccentric ring 33 is substantially smaller in diameter than the coaxial ring 28 and is disposed inside the latter with one side of its outer edge 37 close to the coaxial ring, and with the ring extending partially across the inside of the coaxial ring and beyond the axis 15. With this arrangement, the tool has a dual abrading action. which has been found to have marked advantages over conventional, singleaction heads in the area of rapidity of stock removal and also in ease of control by the operator.
As shown in FIGS. )2 and 4, the eccentric ring 33 herein comprises a plurality of arcuate sections similar to the sections of the coaxial ring 28, but having a shorter radius of curvature, and fastened to the disk 23 by bolts 35 inserted through the disk and threaded into the ring sections. The heads of both sets of bolts 29, 35 are recessed into the upper side of the head below the level of the flange 24.
It will be seen in FIG. 2 that the eccentric ring 33 preferably abuts against the inner edge 37 of the coaxial ring 28, and has an outside diameter larger than the radius of the. coaxial ring but substantially smaller than the inside diameter of the coaxial ring. Thus, during rotation of the head, the eccentric ring covers the space within the coaxial ring with an eccentric, sweeping action. To offset the eccentric weight of the second ring 33, an arcuate counter-balancing weight 38 should be secured to the other side of the head, as indicated in FIG. 2.
Contrary to what might be expected, the dual-action tool 10 is more easily controlled than prior, single-action tools which tend to walk on the work surface rather than remaining substantially stationary unless moved by the operator. More importantly, the rate of stock removal is significantly greater, so that the improved tool results in a material saving in finishing time and, therefore, in cost.
From the foregoing, it will be evident that the improved 3 tool is-relative'ly simple and inexpensive in construction and is readily interchangeable with the single-action tools presently in use. Thus, the improved cutting action and easier control may be obtained 'with presently available finishing machines. It also will be apparent from the foreing that, while a particular form of the invention has been illustrated anddescribed, and a specific use has been suggested, various modifications and other uses can be made without departing from the spirit and scope of the invention. V
I claim as my invention: 1. A rotary abrading tool for polishing generally fiat surfaces, said tool comprising:
a head mountable for coaxial rotation about a movable vertical axis and having a fiat underside disposed in a plane perpendicular to said axis; a first tool ring fastened to said underside in coaxial relation with said head and having a fiat side surface facing away from said head; a'first circular series of polishing elements distributed around said fiat side surface and each comprising an elongated layer of diamond abrasive particles bonded to said first ring to revolve sideways around said axis during rotation of said head; a second tool ring smaller than said first ring disposed inside the latter and fastened to said underside in eccentric relation with said head, said second ring extending from the inner side of said first ring to L beyond said axis thereby to rotate eccentrically within the first ring;
and a second circular series of polishing elements, similar to said first elements, distributed around said second ring.
2. An abrading tool as defined in claim 1 in which said head is a disk and said rings are composed of sections around said ring and each comprising a bar of abrasive material bonded to said fiat side;
a second tool ring smaller than said first ring disposed inside the latter and fastened to said head in eccentric relation therewith, said second ring having a flat side disposed in coplanar relation with the flat side of said first ring;
and a second circular series of abrading elements spaced around said second ring and each comprising a bar of abrasive material bonded to said second flat side in coplanar relation with said first elements, whereby said first elements revolve about said axis while said second ring rotates eccentrically about said axis within said first ring to finish the surface with a dual abrading action.
4. A rotary abrading tool as defined in claim 3 in which said bars are elongated layers of diamond particles bonded to said sides, and inclined relative to the radii of said rings.
5. A rotary abrading tool as defined in claim 3 in which said second ring is disposed inside said first ring with its outer edge closely adjacent the inner edge of the first ring and with said axis extending through both of said rings.
6. A rotary tool for abrading generally fiat surfaces, said tool comprising:
a head mountable for rotation about a predetermined axis and having a working side perpendicular to said axis;
first and second tool rings of different sizes fastened to said working side and having working side surfaces facing away from said head, the smaller of said rings being mounted Within the larger and one of said rings being coaxial with the head, the other being eccentrically mounted;
and two series of abrading elements on the side surfaces of said rings in coplanar relation for simultaneous engagement with a surface to be abraded.
References Cited UNITED STATES PATENTS OTI-IELL M. SIMPSON, Primary Examiner