GB2238236A - Rotary brushes - Google Patents

Abstract

From the backing disc (2) of a rotary brush there depends an annulus of stripping or scarifying wires (4). The wires surround a central region (6) in which there are location and attachment holes (8) for the brush. At one or more of the holes the bottom face of the central region has a recess (12) to receive locking means for the associated attachment element but at least a substantial part of the disc radially inwards of the annulus of wires remains substantially unrecessed. <IMAGE>

Description

ROTARY BRUSHES This invention relates to rotary brushes, especially wire brushes used for stripping and scarifying surfaces.

Rotary brushes are employed in many floor cleaning machines, eg. of the kind shown in GB 689900. The brush comprises a circular backing disc, typically of wood, which may have a sheet metal backing on its upper face.

Passing through the disc in a radially inner region there is a series of holes located on a concentric pitch circle for attachment elements, eg. bolts or pins, securing the disc to a vertical-axis drive of the cleaning machine, and the brush wires are held on the disc in a wide annular band concentric to that inner region and the pitch circle of the holes. The attaching elements project below the lower surface of the disc to receive locking means, such as nuts or circlips, fixing the brush in place.

The projection of the attaching elements below the backing disc reduces the life of the brush because, as the wires wear away with use, these elements will come into contact with the floor or other working surface if the brush is not discarded before the wires have worn down fully.

It has been proposed that the circular inner region within the annulus of brush wires should be offset upwards relative to the annular portion carrying the wires, so that the attaching elements do not project below the roots of the wires, but that can weaken the backing disc which would then have to be reinforced against the danger of fracture under the arduous conditions in which this type of equipment is used.

According to the present invention, in the central region of the backing disc surrounded by the annulus of brush operating elements such as wires, at least one of the holes for the attachment elements opens onto a recess for receiving locking means for the associated attachment element or elements, but at least a substantial part of the disc radially inwards of the annulus of operating elements remaining substantially unrecessed.

To avoid unbalanced centrifugal forces, the recess or recesses should be disposed or distributed symmetrically with respect to the rotary axis of the brush.

In a four-element attachment, preferably only one diametrically opposite pair of holes have said recess or recesses.

The accompanying diagrammatic drawings illustrate examples of the invention. In the drawings: Fig. 1 shows a backing disc for a brush according to the invention in axial section, Fig. 2 is a plan view of the inner region of the brush of Fig. 1, within the brush wire annulus, and Figs. 3 and 4 are similar views of a second embodiment of the invention.

The circular wooden disc of Figs. 1 and 2 has a main outer annular region 2 into which are fixed wire bristles (indicated only by the dotted lines 4 that show the inner boundary of the annulus) surrounding a circular inner region 6 in which there are four location and attachment holes 8 arranged on a pitch circle concentric with the wire brush annulus, and a fifth hole 10 at the centre of the disc.

A diametrically opposite pair of the holes 8 are counterbored from the lower face of the disc. To accommodate the counterbores 12 the inner region is stepped at 14 to give it an increased thickness in comparison with the outer annular region 2 holding the bristles. These counterbores 14 are of a size to hold and allow access to locking elements (not shown) that fit on the bolts or pins (not shown) received in the holes to secure the brush, in known manner, to a floor cleaning machine. The attachment means for the brush can thus be kept from projecting below the bottom face of the annular region 2 of the disc.

It should be noted that counterbores 14 remove very little material, so that they have little weakening effect on the backing disc, and that is compensated for by the increased thickness of the inner region 6. The driving torque for the brush is still transmitted through all four attachment elements and the two attachment elements located in the counterbored holes 8 provide sufficient security to ensure the brush remains in position during use.

In the example of Figs. 3 and 4, similar parts to those already described are given the same reference numbers. There is now a single slot-like recess 22 running between two diametrically opposite holes 8. If the longitudinal axis of the recess 22 runs in the direction of the grain of the wooden backing disc there is no further weakening than with the first example, and in fact the recess 22 can be narrower than the counterbores 12 in the first example without impeding access to the attaching elements associated with that pair of holes.

Claims (7)

1. A rotary brush having a backing disc carrying an annul us of operating elements such as wires coaxial with a rotary axis of the brush and surrounding a central region in which the backing disc has holes for attachment elements, at least one of the holes for the attachment elements opens onto a recess for receiving locking means for the associated attachment element or elements, but at least a substantial part of the disc radially inwards of the annulus of operating elements remaining substantially unrecessed.

2. A rotary brush according to claim 1 wherein the disc has an increased height in said central region.

3. A rotary brush according to claim 1 or claim 2 wherein the recess or recesses are disposed or distributed symmetrically with respect to the rotary axis of the brush.

4. A rotary brush according to any one of claims 1 to 3 wherein one or more of the holes are not associated with a said recess.

5. A rotary brush according to claim 4 for use with a mounting comprising a diametrically opposite pair of attachment elements, the holes for said elements opening onto a recess that extends diametrically across the backing disc, and at least one further attachment element hole opening onto essentially the unrecessed face of the backing disc.

6. A rotary brush according to claim 5 having a wooden backing disc and said diametrical extent of said recess lies in or near the direction of the grain in the wooden disc.

7. A rotary brush constructed and arranged for use substantially as described herein with reference to the accompanying drawings.