Field of the Invention

The present invention relates to polishing apparatus and polishing picks employed for such apparatus, principally for polishing concrete surfaces such as floors. It will be convenient to describe the present invention as it applies to concrete polishing but it should be appreciated that the invention is not limited to concrete polishing and could, for example, also have application for polishing surfaces which are other than concrete, such as ceramic paving, stone, terrazzo and asphalt.

Background of the Invention

Concrete floors and walls can be polished to create a pleasing appearance and to improve the surface quality of the floor or walls. Polished concrete can be suitable for factory and warehouse floors, because it is hard wearing, easy to clean, resistant to oils and acids and the like and can be readily painted or marked as may be required in such commercial premises. For mainly aesthetic reasons, polished concrete flooring is also gaining popularity in domestic residences, such as warehouse apartments. Polished concrete has become an alternative to other surface materials such as marble, paving titles and linoleum or carpet.

Summary of the Invention

According to the present invention there is provided a polishing pick which comprises: a cylindrical shank for receipt within a bore of a polishing apparatus; a platform for supporting a polishing substrate extending from one end of the shank; and a polishing substrate attached to the platform; securing means associated with the shank to secure the shank within the bore of the polishing apparatus and to facilitate free rotation of the shank

relative to the bore of the polishing apparatus when the shank is inserted into the bore.

Amongst other advantages, a polishing pick according to the invention can be reliably secured to a polishing head by receipt of the shank and the securing means within the bore of such a head. This differs from some prior art pick assemblies, which employ a tapered bore into which the shank of the pick assembly is driven and it is the shank which frictionally engages the bore surface to maintain the pick assembly relative to the polishing head. In this arrangement, the shank is driven into the bore, such as by a mallet, hammer or hydraulic piston, and the impact load applied to a pick assembly can be such as to loosen other pick assemblies which have already been secured in place. Moreover, the securing means of the present invention allows the polishing pick to rotate during a polishing operation and this promotes more even wear of the polishing substrate so that the life of the polishing pick is maximised.

The securing means preferably includes a sleeve which is secured to and loosely disposed about the shank so that the shank can freely rotate relative to the sleeve. In this arrangement, the sleeve is arranged to frictionally engage the surface of a bore of a polishing head or machine and in this manner, the shank can be secured against removal from the bore, yet maintaining the required ability to freely rotate. It is the outer surface of the sleeve which engages the inside surface of the bore.

In the above embodiment, the sleeve can be formed with a lengthwise split so permitting the sleeve to be collapsed radially inwardly for insertion into a bore and the sleeve can then resiliently expand after insertion to frictionally engage the bore surface and to thereby fix the polishing pick in place. In order to secure the shank axially to the sleeve, the shank can be formed with an annular groove and the sleeve can include at least one projection for receipt within the groove. Thus, receipt of the projection within the groove secures the shank axially relative to the sleeve, but the annular extent of the groove permits the shank to fully rotate within the sleeve. Other arrangements can be employed for this purpose, such as a circlip arrangement.

Preferably each of the platform and the polishing substrate are circular and in that arrangement, it is preferred that the diameter of the platform and the polishing substrate are either substantially the same, or that the diameter of the platform is less than, preferably slightly less than, the diameter of the polishing substrate. In a preferred arrangement, the diameter of the polishing substrate is about 50 mm although it could easily be larger or smaller. The diameter of the platform can be slightly smaller than that of the polishing substrate, or it can be about the same diameter, or the platform can be large enough to encase the substrate. In the last arrangement, the polishing substrate can be partially received within a recess in the platform.

The polishing substrate preferably is industrial diamond, although the following polishing substrate materials could also be employed: polycrystalline diamond, silicon diamond or tungsten carbide.

It is preferred that location means be provided to locate the polishing substrate in position relative to the platform before the polishing substrate is fixed to the platform. In one arrangement, the location means can comprise a lug which projects from one of the platform or the polishing substrate and which is arranged for receipt within an opening provided in the other of the platform or the polishing substrate. The lug can be a key or a pip, or any other suitable projection.

For properly fixing the polishing substrate to the platform, it is preferred that the polishing substrate have a generally planar base surface which sits flush against a generally planar supporting surface of the platform. By this arrangement, a contact area between the polishing substrate and the platform is across substantially the full base surface of the polishing substrate so that a broad contact area is provided. Preferably the manner of attaching the polishing substrate to the platform is by brazing.

For a better understanding of the invention and to show how it may be performed, embodiments thereof will now be described, by way of non-limiting example only, with reference to the accompanying drawings.

Brief description of the Drawings

Figure 1 is a side view of a polishing pick according to one embodiment of the invention.

Figure 2 is a side view of a polishing head according to the invention.

Detailed Description

Referring to Figure 1 , a polishing pick 10 according to the invention includes a shank 11 , a platform 12 and a polishing substrate 13. In the embodiment illustrated, each of the shank 11 , the platform 12 and the polishing substrate 13 are cylindrical and coaxial.

The shank 11 and the platform 12 can be formed as integral components, and preferably they are formed of steel. The polishing substrate 13 can be of any suitable material depending on the particular purpose to which the polishing pick is to be applied, and if the material being polished is concrete, preferably the polishing substrate is an industrial diamond material. As shown, the axial height H _p of the platform 12 is about equal to the axial height H _ps of the polishing substrate. In practice, the typical platform height H _p and the axial height H _ps of the polishing substrate could have dimensions very different to that shown. For example, the H _p could be twice that of the height H _ps and vice versa.

It is preferred that the diameters of both of the platform 12 and the polishing substrate 13 are about the same, or as shown, that the diameter of the polishing substrate 13 slightly exceeds that of the platform 12. It is however acceptable for the diameter of the platform 12 to be greater than the diameter of the polishing substrate 13.

The polishing pick 10 includes securing means associated with the shaft 11 and in Figure 1 , the securing means comprises a sleeve 14 which is loosely disposed about the shank 11 but is secured. axially thereto. Thus, the shank 11

can rotate relative to the sleeve 14 about its lengthwise axis, but is secured against significant axial movement relative to the sleeve 14. The sleeve 14 is secured axially to the shank 11 , by receipt of a radially inwardly extending protrusion 15 which extends into a annular groove 16 formed in the shank 11.

The sleeve 14 includes a lengthwise split 17 and by the provision of the split 17, sleeve 14 can be collapsed radially inwardly, to insert the sleeve 14 and the shank 11 into the bore of a polishing head. Once inserted, the sleeve 14 can be allowed to resiliently expand and frictionally engage the surface of the bore and that frictional engagement secures the sleeve 14 within the bore and so secures the shank 11 against removal from the bore. Advantageously however, the shank 11 is rotatable within the bore by this arrangement and allows the polishing pick 10 to rotate during a polishing operation.

A flange 18 is provided and this can be loosely fitted or fixedly secured about the sleeve 14 and is in engagement with the underneath surface 19 of the platform 12. The flange 18 can provide shock absorption qualities between the platform 12 and the polishing head to which the polishing pick 10 is fitted.

With reference to Figure 2, a polishing head 30 is shown including a plurality of polishing picks 31 in accordance with the polishing pick 10 shown in Figure 1. The polishing or working surfaces 31 A of each pick 31 are co-planar and can include a central recess 31 B as shown. Each polishing pick 31 extends from a circular base 32 which is formed as a disc with the shank 35 and sleeve 34 received within a bore 33 (shown in broken outline) of a mounting knuckle 36. Each bore 33 extends generally perpendicular to the plane of the base 32 so that each of the picks 31 is also oriented substantially perpendicular to the general plane of the base 32. The sleeve 34 frictionally engages the bore 33, while as discussed earlier, the shank 35 is rotatable about the lengthwise axis A but cannot shift axially relative to the sleeve 34.

The mounting knuckles can be fixed to the base 32 by any suitable arrangement, and in the illustrated arrangement, they are fixed to the base 32 by welding.

The working surfaces 31 A can include an outside ring defining an internal recess 31 B. In this form of working surface, the surface has less wear area and therefore can wear for more consistent polishing pattern.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.