Patent Publication Number: US-6217431-B1

Title: Sanding brush assembly

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the priority of German Patent Application Serial No. 298 04 936.8, filed Mar. 19, 1998. 
     BACKGROUND OF THE INVENTION 
     The present invention relates, in general, to a sanding brush assembly, and more particularly to a sanding brush assembly of a type having a metallic base body formed about its circumference or on its end face with grooves spaced at an angular distance from one another for detachably receiving in form-fitting or force-fitting engagement clamping elements of strip brushes, with sanding segments being secured to the base body between the strip brushes and supported by the strip brushes. 
     These types of sanding brush assemblies are also known as rotary brushes and can be used in sanding machines for sanding, dusting, cleaning, polishing and structuring of wood, metal, plastics or the like. The base body has a bore for placement on a sanding shaft, with the strip brushes containing an array of bristles made, for example, of horsehair, wire, abrasive grain, fiber or other like material. 
     The sanding segments form the sanding means and rest upon the strip brushes trailing in direction of rotation of the base body, thereby realizing also a sanding action of uneven or profiled workpieces. These sanding segments are subject to wear so that the sanding action deteriorates after a certain sanding operation. In conventional sanding brushes, the sanding segments extend into the interior of the base body, thereby forming a reserve which is used to compensate progressive wear of the sanding segments. This, however, requires the operator to, for example, loosen screw fasteners in order to pull out the sanding segments by a certain length. Thus, the readjustment of the sanding segments becomes rather cumbersome. Moreover, a relatively great length of sanding segments remains as residue, when further compensation of wear is no longer possible. This length is defined as the distance of the outer edges of the strip brush from the outer surface or end face of the base body. 
     SUMMARY OF THE INVENTION 
     It is thus an object of the present invention to provide an improved sanding brush assembly, obviating the afore-stated drawbacks. 
     In particular, it is an object of the present invention to provide an improved sanding brush assembly which is so configured as to significantly reduce the amount of waste, thereby increasing the overall efficiency. 
     It is still another object of the present invention to provide an improved sanding brush assembly which is so configured as to allow attachment of a greater number of sanding segments. 
     These objects, and others which will become apparent hereinafter, are attained in accordance with the present invention by securing each of the sanding segments to a flexible footing whereby the flexible footing of the sanding segment is clamped together with the clamping element of the strip brushes in the groove of the base body. 
     In accordance with the present invention, the base body is thus freed from direct attachment of the sanding segments. The flexible footing is so configured that the dimension of the attached sanding segment is substantially smaller than the wasted residue experienced in conventional sanding brushes and no longer suitable for use. As the flexible footing is mounted together with the strip brush in the groove, the need for separate fasteners to secure the sanding segments is eliminated. Replacement of sanding segments can thus be carried out in an extremely short period as the grooves and the clamping elements of the strip brushes are designed for a positive or form-fitting engagement. This can, for example, be realized by grooves of dovetail cross section. 
     Suitably, the attachment between the flexible footing and the sanding segment is realized outside the base body. As sanding brushes are operated at fairly high speed, the sanding segments are prevented from detachment from the grooves when exposed to centrifugal forces, by configuring the footing in such a manner that at least the area clamped in the groove has an angular or U shaped configuration and encompasses the clamping element. 
     According to another feature of the present invention, the bottoms of the grooves extend at least along two different circles, when, according to one configuration of the sanding brush assembly, the strip brushes are attached about the circumference of the base body, whereby the bottoms of the grooves are disposed in alternating distance to the axis of rotation of the sanding disk, or at least in two different planes when, according to another configuration of the sanding brush assembly, the strip brushes are attached on the end face of the base body, whereby then the bottoms of the grooves are disposed in alternating distance to the end face. Thus, as grooves are provided of at least two different depths, the use of the sanding segments is further optimized because the sanding segments can first be placed in those grooves whose bottoms are at a greatest distance to the perimeter or end face of the base body. After worn out to a certain extent, the sanding segments can then be repositioned into those grooves whose bottoms are at a smaller distance to the perimeter or end face of the base body. Thus, the sanding segments can be used up almost completely. 
     Suitably, the grooves are disposed in the base body according to a pattern. It is, for example, advantageous to arrange the grooves of varying depths in alternating relationship because it allows to shorten the angular distances between the grooves compared to conventional designs. Thus, the number of strip brushes and the number of sanding segments may be increased about the circumference or end face of the base body, thereby realizing a significantly improved sanding result. It is possible, to increase the number of strip brushes and sanding segments by about 40%. 
     Moreover, in the embodiment of the sanding brush assembly with strip brushes and sanding segments attached at the end face, the attachment of the strip brushes and the sanding segments to the base body may be realized in a star-shaped manner. 
     According to another feature of the present invention, each flexible footing has a section projecting beyond the perimeter or end face of the base body, with the outwardly projecting section being of arcuated configuration. The sanding segment is then so shaped as to conform to the shape of the arcuate section. While the deformability of the strip brushes is limited, the sanding segments are so configured as to deform to a greater extent. In this manner, the range of application of the sanding brush is expanded as the risk of damage of the workpiece being ground is significantly reduced, and wear of the sanding segment is decreased as a result of the diminished impact force upon contact with the workpiece being ground. The arcuate section may have any desired curvature or curved pattern. Preferred however is a configuration in which the outer edges are positioned at a greater distance to the associated strip brush than the mid-region. Regardless of the configuration of the sanding brush, the sanding segments are provided at least in the outer zone distal to the flexible footing with longitudinal indentations. 
     A sanding brush assembly according to the present invention is also utilized for handling profiled bars of varying cross sections, whereby the design of the strip brushes and the sanding segments depends on the cross sections of the profiled bars. Advantageously, the flexible footing extends into the area of the outer free edge of the pertaining strip brush, with the sanding segment being secured to the outer free edge of the flexible footing. As in this configuration, the external contour of the strip brush and the matching contour of the sanding segment are suited to the cross section of a profiled bar, it is proposed in accordance with the present invention to provide a support pad between the array of bristles of the strip brush and the flexible footing, whereby the support pad is preferably secured to the array of bristles. Thus, the support pad is positioned, when viewed in circumferential direction of the sanding brush, in front of the strip brush. This enhances the sanding action, as the support pad is not deformed as strongly as the strip brush. 
     According to another feature of the present invention, the support pad is made of cellular rubber or similar elastically deformable material. Regardless of the configuration of the sanding brush, the sanding segments and the strip brushes may advantageously be designed as profiled elements to suit them to varying cross sections of the objects being treated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features and advantages of the present invention will now be described in more detail with reference to the accompanying drawing, in which: 
     FIG. 1 is a schematic illustration of one embodiment of a sanding brush assembly according to the present invention; 
     FIG. 2 is a schematic illustration of another embodiment of a sanding brush assembly according to the present invention; 
     FIG. 3 is a cutaway view, in developed illustration, of grooves for receiving strip brushes and sanding segments; 
     FIG. 4 is a perspective view of a sanding segment attached to an elastic footing; 
     FIG. 5 is a fragmentary, partially sectional view, in exploded illustration, of still another embodiment of a sanding brush assembly according to the present invention; and 
     FIG. 6 is a simplified, schematic illustration of an exemplified sanding brush assembly with strip brush and sanding segments as profiled elements. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Throughout all the Figures, same or corresponding elements are generally indicated by same reference numerals. 
     Turning now to the drawing, and in particular to FIG. 1, there is shown a schematic illustration of one embodiment of a sanding brush assembly according to the present invention, generally designated by reference numeral  10  and essentially including a metallic base body  11 , a plurality of strip brushes  12  which are spaced about the perimeter of the base body  11 , and a like number of sanding segments  13  which are disposed between the strip brushes  12 . Thus, in a  16  direction of rotation of the sanding brush assembly  10 , as indicated by arrow A, the strip brushes  12  trail the sanding segments  13  and thus form a support for the sanding segments  13 . FIG. 2 shows another embodiment of a sanding brush assembly  10 ′ which differs from the sanding brush assembly  10  of FIG. 1 merely by the disposition of the strip brushes  12  and sanding segments  13  on one end face of the base body  11 . Thus, as a comparison of FIGS. 1 and 2 shows, the outside diameter of the base body  11  of the sanding brush assembly  10 ′ is significantly greater than the outside diameter of the base body  11  of the sanding brush assembly  10 . FIGS. 1 and 2 also show that the outer free ends of the sanding segments  13  slightly extend beyond the ends of the strip brushes  12 . 
     Turning now to FIG. 3, there is shown a schematic illustration of an attachment of the strip brushes  12  and the sanding segments  13  in the base body  11  of the sanding brush assemblies  10 ,  10 ′. In the embodiment of FIG. 1, the base body  11  of the sanding brush assembly  10  is formed with grooves  14  spaced about the perimeter and extending across the entire width of the base body  11 . In the embodiment of FIG. 2, the grooves  14  are formed in one annular end face and extend from the end face. Reference numeral  15  denotes in FIG. 3 a surface which may represent the circumferential surface of the base body  11  of the sanding brush assembly  10  or the annular end face of the base body  11  of the sanding brush assembly  10 ′. 
     The grooves  14  have two different depths and are arranged in alternating disposition so that the bottoms  14   a  of the grooves  14  of the sanding brush assembly  10  extend along two different diameters with respect to the circumferential surface  15 , while the bottoms  14   a  of the grooves  14  of the sanding brush assembly  10 ′ extend in two planes with respect to the annular end face  15 . The depth of the grooves  14  with greater distance of the bottoms  14   a  to the circumferential surface or end face  15  is about double the depth of the grooves  14  of smaller distance. Persons skilled in the art will understand that the arrangement of grooves with two different depths in the base body  11  is shown by way of example only. It is certainly within the scope of the present invention, to provide an arrangement of grooves of more than two different depths. 
     As shown in FIG. 3, the grooves  14  of smaller depth have a dovetail configuration, while the grooves  14  of greater depth have a first part of tetragonal configuration which is followed by a second part of dovetail configuration. Each of the strip brushes  12  is received in a clamping element  17  which is inserted in the associated groove  14  and conforms to the shape thereof so as to realize a form-fitting engagement of the strip brushes  12  in the grooves  14 . A positive engagement may also be realized by T-shaped grooves. 
     The attachment of the sanding segments  13  and the strip brushes  12  in the grooves  14  is identical for each sanding segment and strip brush so that their attachment will hereinafter be described in detail with reference to one exemplified sanding segment  13  and strip brush  12 . 
     As shown in particular in FIG. 4, the sanding segment  13  is secured, preferably by gluing, outside the base body  11  to a flexible footing  16  which has an angled lower end  16   a  distal to the sanding segment  13 . In the area distant to the flexible footing  16 , the sanding segment  13  is formed with longitudinal indentations  20 . The footing  16  is insertable with its lower end  16   a  into the dovetailed section of the groove  14  of greater depth such as to encompass the clamping element  17  which holds the bristles of the strip brush  12  together (cf. FIG.  3 ). When the strip brush  12  and the sanding segment  13  wears off to a certain extent following a sanding operation, the strip brush  12  and the sanding segment  13  can then merely be removed from the groove  14  of greater depth and inserted into the groove  14  of smaller depth to thereby re-establish the full sanding action. 
     Persons skilled in the art will appreciate that the lower end  16   a  of the flexible footing  16  may also be of U-shaped configuration. 
     The area of the flexible footing  16 , projecting out of the footing body  11 , forms the attachment zone for the sanding segment  13  and is so arched with respect to the strip brush  12  that the outer edge of the sanding segment  13  extends at a greater distance to the strip brush  12 , which trails the sanding segment  13  in direction of rotation A, than a mid-region thereof. However, it will be understood that the curvature may also be designed in opposite direction. The arched area of the footing  16  realizes also a deformation of the attached sanding segment  13 . This design is advantageous during sanding as the risk for damage of the workpiece being ground is significantly reduced. FIG. 4 also shows that the free edge of the flexible footing  16  extends along an arc directed toward the base body  11 . 
     Turning now to FIG. 5, there is shown a fragmentary, partially sectional view, in exploded illustration, of still another embodiment of a sanding brush assembly according to the present invention, generally designated by reference numeral  10 ″. Again, it is noted that same reference numerals are used for same elements as described in the preceding description. The sanding brush assembly  10 ″ is particularly suitable for working on profiled bars, and includes a strip brush  12  in the form of bristles restrained in a clamping element  17 . The outer contour of the strip brush  12  and thus also the contour of the sanding segment  13  is suited to the cross sectional configuration of profiled bars to be handled. The contour of the strip brush  12  may be stepped, arched or the like. 
     Disposed between the flexible footing  16  and the array of bristles of the strip brush  12  is a support pad  18  which is made of cellular rubber. The support pad  18  extends over the entire length of the bristles of the strip brush  12 . In the non-limiting example of FIG. 5, the support pad  18  is glued to the strip brush  12 . In the assembled state, the flexible footing  16  encompasses the support pad  18  and is so shaped that the upper free edge of the footing  16  reaches into the area of the free edge of the bristles and lap over the support pad  18 , with the sanding segment  13  being mounted to the overlapping edge of the footing  16 . Also the lateral walls of the support pad  18  are enveloped by the footing  16  which is a formed body conforming to the shape of the support pad  18 . 
     In direction of rotation of the sanding brush assembly  10 ″, indicated by arrow A, the support pad  18  is positioned in front of the bristles of the strip brush  12 . 
     Also in this embodiment, the consumption of material for the sanding segments  13  is significantly reduced compared to conventional constructions. Moreover, the sanding segments  13  can almost entirely be used up as a consequence of the different depths of the grooves  14 . 
     FIG. 6 shows, by way of example only, sanding segments  13  and strip brushes  12  as profiled elements, whereby the sanding segments  13  and the strip brushes  12  have, for example, a curved configuration to suit to a complementary curved object being treated. Of course, the sanding segments  13  and the strip brushes  12  may have different configurations to suit respective cross sections of the objects being treated. 
     While the invention has been illustrated and described as embodied in a sanding brush assembly, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.