Polishing apparatus having an expandable head

An apparatus for polishing a metal article, including a tapered mandrel adapted to be connected to a power source. The tapered mandrel is received within the tapered interior of an expandable hub that is provided with a plurality of longitudinally extending slots. One group of slots extends from one end of the hub and terminates short of the opposite end of the hub, while a second group of slots is spaced between the first slots and extend from the second end of the hub and terminate short of the first end. A series of outwardly projecting longitudinal ribs are located between adjacent slots. The hub is positioned within a resilient sleeve having a plurality of internal longitudinal grooves to receive the ribs, and the outer surface of the sleeve receives an abrasive band. By threading a stud in the outer end of the mandrel, the tapered mandrel is drawn inwardly of the hub to expand the hub and firmly secure the abrasive band to the sleeve. Through use of the ribs, an effective power transmission is obtained between the mandrel and the abrasive band to accommodate high speed, high pressure polishing of metal articles.

BACKGROUND OF THE INVENTION 
Polishing of metal articles, such as kitchen sinks, cookware, etc., is 
normally carried out under high speed conditions, up to 7,000 rpm, and 
with substantial pressure being applied by the polishing head to the metal 
workpiece. It is important in polishing metal articles to have a positive 
drive transmission between the driving source and the abrasive band to 
prevent slippage of the band during the high speed, high pressure 
operating conditions. 
In the past, a typical polishing head has been composed of a central 
rotatable shaft with a rubber sleeve bonded to the shaft. The outer 
surface of the rubber sleeve has been provided with a series of 
circumferentially spaced, longitudinal slots that are cut at an angle to 
the radius of the sleeve. The abrasive band is manually installed on the 
rubber sleeve by twisting the sleeve in a direction to compress the slots, 
thereby reducing the external diameter of the sleeve, and then slipping 
the band over the compressed sleeve. Installation of the abrasive band is 
a very difficult operation, requiring considerable strength and dexterity, 
particularly when the polishing head is mounted vertically in a polishing 
machine. Depending on the particular article being polished, it is often 
necessary to replace the abrasive band numerous times during a working 
shift. 
It is also known in the woodworking art to mount a sandpaper belt on an 
expandable hub, as shown in U.S. Pat. Nos. 1,395,468, 154,756, 1,570,166 
and 2,083,793. In this type of construction, as described in the 
aforementioned patents, a tapered mandrel is inserted within an expandable 
hub, causing the hub to expand radially and grip the abrasive band. 
However, this type of mounting of the abrasive band, while operable under 
low speed conditions on wood, has not been successfully employed with high 
speed, high pressure metal polishing operations. 
SUMMARY OF THE INVENTION 
The invention is directed to an improved apparatus for polishing metal 
articles, and more particularly to a polishing head having an improved 
mechanism for mounting an abrasive band. In accordance with the invention, 
the polishing head includes a tapered mandrel which is received within the 
tapered interior of an expandable hub. The hub is provided with a first 
group of longitudinally extending slots that extend from one end of the 
hub and terminate short of the second end. In addition, the hub is 
provided with a second group of longitudinal slots which are spaced 
between the first slots and extend from the second end of the hub and 
terminate short of the first end. 
In addition, the hub is provided with a plurality of outwardly extending 
longitudinal ribs which are located between adjacent slots. 
Located outwardly of the expandable hub is a resilient, rubber-like sleeve 
having a plurality of internal grooves which receive the ribs on the hub. 
The abrasive band is positioned on the outer surface of the resilient 
sleeve. 
By threading a stud into the outer end of the mandrel, the tapered mandrel 
is drawn into the hub, thereby expanding the hub and providing a firm 
connection between the driving source and the abrasive band. 
Due to the external ribs on the hub that mate with grooves in the resilient 
sleeve, a positive transmission of power is achieved between the hub and 
the sleeve which prevents slippage under high speed, high pressure 
polishing operations. 
When worn, the abrasive band can be readily replaced by loosening the stud 
to contract the hub. With the hub contracted the abrasive band can be 
slipped off of the polishing head and the new band installed. By 
tightening the stud, the hub will be expanded to firmly secure the band to 
the resilient sleeve. 
As an additional feature of the invention, the ends of the expandable hub 
are engaged within grooves in the mandrel and in the stud. The engagement 
of the ends of the hub with the grooves prevents the hub from flying 
outwardly in the event the hub should fracture under high speed operation. 
Other objects and advantages will appear in the course of the following 
description.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
FIG. 1 illustrates a polishing head 1 which can be used for polishing metal 
articles, such as kitchen sinks, cookware, or the like. In practice, the 
head 1 is normally installed vertically in a polishing machine, but in 
certain installations, it may assume different orientations. 
Polishing head 1 includes a tapered mandrel 2 and the upper end of mandrel 
2 is provided with a tapped hole 3 which receives the end of a driving 
spindle 4 that is connected to a suitable source of power to thereby 
rotate the polishing head about its axis. 
Mandrel 2 has an outer tapered body 5 which is received within the upper 
tapered interior 6 of an expandable hub 7. The lower end of hub 7 is 
provided with a lower tapered section 8 which communicates with upper 
tapered section 6 and diverges downwardly and outwardly. The tapered 
section 8 provides the lower end of the hub with a thickness similar to 
that of the upper end of the hub so that both ends of the hub will expand 
generally uniformly. 
As best shown in FIGS. 2 and 5 the upper end 9 of hub 7 is received within 
an annular groove 10 formed in the flange of mandrel 2, while the lower 
end 11 of hub 7 is received within a groove 12 formed in the flange 13 of 
threaded stud 14. However, ends 9 and 11 do not bottom out in the 
respective grooves 10 and 12. Stud 14 is threaded within a tapped opening 
in the end of mandrel 2, and by threading down of stud 14, the tapered 
mandrel will be drawn inwardly within the hub 7, causing the hub to expand 
radially outward. 
To facilitate the threading down of stud 14, the outer end of the stud is 
provided with a hex-shaped opening 15 into which an Allen wrench or other 
tool can be inserted. Threads on stud 14 are of the opposite hand from the 
direction of rotation of the head to prevent loosening of the stud during 
operation. 
Hub 7 is provided with a plurality of longitudinally extending slots 16. 
One group of slots 16a extend from the lower end of the hub and terminate 
at a base 17a spaced from the upper end of the hub, while a second group 
of slots 16b extend from the upper end of the hub and terminate at a base 
17b spaced from the lower end of the hub. 
As best shown in FIG. 3 each slot 16 is provided with a narrow section 18 
and a wider section 19 which terminates at the base 17. The wider sections 
19 of the slots 16 located adjacent base 17 aid in providing a more 
uniform expansion of the hub 7. 
In addition to slots 16, the hub 7 is also provided with a plurality of 
outwardly extending longitudinal ribs 20 which are located between 
adjacent slots 16. As shown in FIG. 4, each rib 20 is provided with a pair 
of outwardly diverging side walls 21 which terminate in an outer surface 
22. As illustrated in FIG. 3, the ribs 20 extend substantially the entire 
length of the hub 6 and as the hub is expanded, ribs 20 will be deformed 
to a slightly snake-like or sinuous configuration. 
Located outwardly of hub 7 is a resilient sleeve 23 formed of rubber or an 
elastomeric material. Sleeve 23 is provided with a plurality of internal 
grooves 24 which receive ribs 20 on hub 7. In addition, the outer surface 
of sleeve 23 is formed with a series of diagonally extending grooves 25 
and an abrasive band 26 is mounted on the outer surface of sleeve 23. 
Grooves 25 aid in the polishing operation by providing a relief for swarf 
and they also reduce the noise level. 
The polishing head 1 is normally installed in an automatic polishing 
machine, although it is contemplated that the polishing head could, in 
some cases, be utilized with a manual tool. In normal operation, the head 
1 is disposed vertically and is adapted to operate against the side wall 
of kitchen sinks or against the side wall of metal cookware. 
To replace the abrasive band 26, stud 14 is loosened, causing hub 7 to 
contract, thereby loosening the connection of the abrasive band 26 to 
sleeve 23. The abrasive band can then be slipped downwardly from the 
polishing head and a new band installed. By threading down the stud 14, 
the tapered mandrel 2 is drawn into the tapered interior 6 of hub 7 
causing the hub to expand outwardly and flanges 10 and 13 bear firmly 
against the ends of sleeve 23 to increase the driving force. Expansion of 
the hub causes a corresponding expansion of sleeve 23 to thereby firmly 
grip the abrasive band 26. 
While the drawings illustrate the ribs 20 as being undercut, it is 
contemplated that the ribs can have other configurations. The undercut 
configuration of the ribs, as shown in FIG. 4, provides more expanding 
power due to the greater surface area at the surfaces 22. 
The ribs 20, in combination with slots 16, provide a hub which can be 
readily expanded yet achieves a positive driving connection between the 
mandrel and the resilient sleeve. 
Various modes of carrying out the invention are contemplated as being 
within the scope of the following claims particularly pointing out and 
distinctly claiming the subject matter which is regarded as the invention.