Abstract:
For use in a concrete floor grinding, polishing or burnishing machines, a combination of a drive plate and abrading pads attached to the drive plate is described. The abrading pads include a planar substrate having one or more posts projecting from a first major surface and a resin layer impregnated with abrasive grit on its second major surface. The drive plate includes areas thereon for receiving the substrate and where the areas each include at least one elongate aperture through which the post extends and when the substrate is shifted laterally, the posts become releasably locked in place.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    None 
       BACKGROUND OF THE INVENTION 
       [0002]    I. Field of the Invention 
         [0003]    This invention relates generally to machines for grinding and/or polishing and/or burnishing concrete, stone and tile flooring and more particularly to grinding heads and resin abrading pads designed for tool-less attachment to the rotatable drive plate of such grinding/polishing machines. 
         [0004]    II. Discussion of the Prior Art 
         [0005]    It is known that concrete and stone or tile surfaces can be made more attractive by first abrading the hardened concrete, stone or tile flooring to yield a smooth, planar surface and then subsequently polishing or burnishing that surface with resin pads to provide a high gloss glaze to the surface. Machines for grinding and/or polishing concrete, stone or tile flooring generally comprise a wheeled frame having a handle extending upward whereby an operator may steer the machine. Mounted on the frame is a motor having a vertical shaft extending through the top surface of a shroud and the shaft is connected to a drive plate within the shroud. Adapted to be affixed to the drive plate is a plurality of diamond grinding heads or a plurality of polishing or burnishing pads depending upon the operation to be performed. 
         [0006]    Grinding heads and polishing or burnishing pads are subject to wear and need to be frequently replaced. It is therefore advantageous to be able to couple the grinding heads or polishing pads, as the case may be, to the drive plate quickly and easily and without the use of tools. Furthermore, the attachment must be in a way that positively locks the heads or pads to the drive plate so that centrifugal and other forces encountered during use do not result in separation of the heads/pads from the spinning drive plate when the machine is operating. 
         [0007]    Examples of prior art approaches for coupling grinding heads to a drive plate are found in U.S. Pat. Nos. 8,272,924 and 8,585,466 to Van Eijden et al. where drive pins and permanent magnets are used to “stick” the heads to the drive plate. The U.S. Published Application 2013/0090047 A1 to Bin teaches the use of Velcro® hook and loop material for releasably joining a polishing tip holder plate to the machine&#39;s drive plate. Neither of these prior art attachment modes is deemed to be totally reliable and may result in unwanted decoupling during use, especially where irregularities in the concrete slab and the angular velocity of the pads induce omnidirectional forces to the floor-engaging pads, adversely impacting their holding power. The use of several dowel pins and permanent magnets as in the Van Eijden patents makes removal and replacement of the grinding heads and polishing/burnishing pads needlessly complicated and time consuming. 
         [0008]    A need therefore exists for an improved way of releasably securing grinding heads and/or polishing or burnishing pads to the drive plate of a floor surface prep machine of the type described that resists decoupling during use and which allows quick replacement without the need for tools. The present invention achieves these ends. 
       SUMMARY OF THE INVENTION 
       [0009]    In accordance with the present invention, there is provided an abrading pad for attachment to a drive plate of a concrete or stone floor finishing machine where the abrading pad includes a planar substrate having a predetermined shape and with first and second major surfaces. Projecting perpendicular to a first major surface of the substrate is at least one post having a flange at a free end. Affixed to the second major surface of the substrate is a resin layer impregnated with an abrasive. 
         [0010]    To affix the abrading pad to a circular metal disk comprising the machine&#39;s drive plate, a plurality of pockets may be formed inwardly from a first major surface, the pockets being regularly circumferentially spaced proximate the peripheral edge of the drive plate. The inclusion of pockets in the drive plate may not always be necessary. Each of the pockets may include at least one elongate aperture that extends through the thickness dimension of the metal disk. The elongate aperture comprises a first segment of a first size at one end and transitioning into a second segment of a second size less than that of the first size at an opposed end of the elongate aperture. The first size of the first segment is larger than the size of the flange on the pad&#39;s at least one post, allowing insertion of the post with the flange through the first aperture segment. The cross-sectional dimensions of the post are approximately the same as the size of the second circular segment such that when the pad is moved laterally, an interference fit is created when the pad is translated relative to the drive plate to the point where the flange is made to underlie the elongate aperture&#39;s second segment. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction with the accompanying drawings in which: 
           [0012]      FIG. 1  is a side elevation view of a polishing pad constructed in accordance with the present invention; 
           [0013]      FIG. 2  is a perspective top view of the polishing pad of  FIG. 1 ; 
           [0014]      FIG. 3  is a bottom perspective view thereof; 
           [0015]      FIG. 4  is a plan view of a machine drive plate designed to accommodate the polishing pad of  FIGS. 1-3 ; and 
           [0016]      FIG. 5  is an enlarged partial view of the drive plate of  FIG. 4 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressively described otherwise. 
         [0018]    Keeping the above points in mind and referring to  FIGS. 1-3  of the drawings, a preferred embodiment of a floor abrading pad is displayed. The pad is indicated generally by numeral  10  and is seen to comprise a planar substrate  12  of a rigid plastic with polyurethane being preferred. The substrate here is shown as having a generally polygonal shape with radiused intersecting sides as seen in the views of  FIGS. 2 and 3 . However, it is to be understood that this shape is somewhat arbitrary and other shapes can serve as well. 
         [0019]    With reference to  FIG. 1 , the substrate  12  is seen to have an upper major surface  14  and a lower major surface  16 . At least one post and preferably first and second posts  18  projects perpendicularly from the lower major surface  16  and formed on the free end of each is a flange as at  20  and  22 . 
         [0020]    Bonded to the upper major surface  14  by a suitable adhesive is a substrate comprising, for example a resin layer  24 , which is preferably partitioned into plural segments by intersecting score lines plainly visible in the view of  FIG. 2 . Intermixed with the resin are synthetic diamonds of a desired grit size. Pads of the type described may be offered with differing grit sizes ranging from course to very fine. 
         [0021]    Having described the constructional features of the floor abrading pads to be used with a floor polishing, burnishing and grinding machine, consideration will next be given to the construction of the drive plate and especially the mode of attachment of the above described abrading pads thereto. 
         [0022]    Referring to  FIG. 4 , a ring portion of a drive plate for attachment to a concrete, stone or tile floor finishing machine is indicated generally by numeral  30  and comprises an annular metal plate member  32  that may have a plurality of pockets  34  of a size and shape to receive a pad  10  therein and that are evenly distributed adjacent the periphery of the annular plate  32 . As an example, and without limitation, with the annular plate  32  may be made of aluminum and may be 9.53 mm in thickness, the depth of the pockets  34  that are machined into the surface of the plate may have a depth of 3.05 mm. Other embodiments of a suitable drive plate may be void of such pockets, allowing a thinner and lighter plate material to be used. For example, a thickness of 6.35 mm for an aluminum ring similar to  FIG. 4  but void of the pockets  34  has proven workable. Also, materials other than aluminum, such as a hard, non-brittle plastic, may be used in fabricating the drive plate. 
         [0023]    Located between each of the pockets  34  is an oval aperture  36  that extends through the thickness dimension of the annular plate  32  and these punched oval apertures  36  function to further reduce the weight of the machine. 
         [0024]    It may also be observed from  FIG. 4  that the pockets  34  generally comprise eight-sided polygons where the intersections between adjacent linear segments are radiused and thus somewhat match the shape of the substrate  16  of the polishing pads  10 . 
         [0025]    Located in each of the pockets  34  is an elongate aperture  38  for receiving each post on the pad  10 . The aperture(s) extend through a thickness dimension of the annular plate  32 . Each of the elongate apertures  38  comprises a first segment  40  of a first size and shape at one end of the elongate apertures  38 , and a second segment  42  of a second size and shape that is less than the first size and shape of the segments  40  and where the two segments are contiguously joined. In  FIG. 4 , the first segment is circular in shape and of a diameter allowing the flange  20 ,  22  to fit through it. 
         [0026]      FIG. 5  is a greatly enlarged partial view of the annular plate  32  and one of the pockets  34  containing the elongated apertures  38  that comprise the first circular segment  40  and the contiguously joined second circular segment  42 . The dashed line  44  in  FIG. 5  is indicative of the fact that the drive plate  32  is undercut on its back side. 
         [0027]    The diameter of the circular segment  40  is only slightly greater than the diameter of the flange  20  on the post  18  of the abrading pad  10  while the diameter of the second circular segment  40  is approximately the same as the diameter of the post  18 . Thus, to affix an abrading pad to the drive plate, one merely inserts the flange  20  through the first circular segment and then laterally translates the pad to move the posts  18  into the second circular segment  42 , and with the flange residing in the undercut represented by the dashed line  44 . Because of the friction fit maintained between the abrading pad&#39;s posts  18  and the walls defining the second circular segment  42 , a predetermined force must be applied by hand to the pad to again shift it so that the flange  20  is again aligned with the first circular aperture  40 , allowing removal of a pad once it has become worn. 
         [0028]    Because of the way that the pads are oriented when affixed to the drive plate in the manner described, it is oriented close to the periphery of the annular plate, thereby providing a maximum angular velocity which is conducive to increased polishing efficiency. Moreover, the high angular velocity results in a centrifugal force on the abrasion pad that serves to hold the abrading pad&#39;s posts in the far end of the drive plate&#39;s elongated aperture. 
         [0029]    This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and be used with a variety of grinding/polishing pads. As an example, rather than utilizing posts of round cross-section, they can be of other cross-sectional shapes. Furthermore, the flanges need not be circular, but should correspond to the shape of the elongated aperture segments so as to be able to be inserted through them. Also, various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.