Abrading – Frame or mount – Portable abrader
Reexamination Certificate
2000-04-14
2001-05-22
Banks, Derris H. (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S359000
Reexamination Certificate
active
06234887
ABSTRACT:
PRIOR ART TECHNIQUE
The invention concerns a method for the sanding of surfaces on items by means of tools which consist of sanding segments which extend radially from a core in the formation of a cylindrical sanding tool, said tool being rotated around an axis of rotation which extends substantially parallel with the surface on the item, so that under the influence of centrifugal force the individual sanding segments exert a sanding pressure against the surface of the item, and where there are mounted several of such tools which are rotated in mutually opposite directions while at the same time being moved in relation to the item, or where the item is moved in relation to the sanding tools.
The sanding of surfaces by means of such tools is used especially for the processing of wooden items whose surfaces must be smooth.
Similarly, in connection with lacquered surfaces, the sanding can be used with advantage as intermediate sanding between lacquer applications.
Moreover, the method can be used for the cleaning of metal surfaces, where the sanding also serves to deburr the edges so that both an effective and uniform deburring is achieved.
Finally, the method can be used for items of plastic where, for example, the surface must be ground with the object of removing fraze and/or for subsequent surface treatment.
Machines are known for the execution of such a method. For example, from the description of DK Patent 156.703, a machine is known for the sanding of wooden items, and which is provided with six sanding rollers in a tool which rotates in such a manner that adjacent rollers are rotated in opposite directions during the turning of the tool over the item.
The individual rollers are rotated at the same speed, i.e. the rollers which rotate clockwise and the rollers which rotate counter-clockwise during the turning of the tool over the item all rotate at the same speed.
However, there hereby arises a small difference in the sanding effect of the individual sanding elements, the reason being that because of the differences in the relative speeds, the individual sanding segments will have different contact pressure, sanding pressure, against the surface of the item.
The sanding elements on the tools rotating in the manner like a roller will namely be fed a little slower over the item, and herewith have a relatively lower sanding effect than the corresponding sanding elements on the tools which rotate in the opposite direction, in that the relative sanding speed of these is higher and the sanding effect therefore greater than that of the tools which rotate like a roller.
This difference in effect results not only in a non-uniform sanding of the surface, but also a non-uniform wear on the sanding elements.
From DK 9300243 Y6 there is known a pass-through sanding machine with sanding tools which have variable speeds of rotation. The object of this is to be able to mount sanding tools successively with different sanding aggressiveness, in that the speed of the individual tools can be set in accordance with their aggressiveness.
THE OBJECT OF THE INVENTION
It is the object of the invention to remedy the disadvantages and drawbacks of the known methods, and this is achieved according to the invention when the sanding tool which moves in the rolling direction over the item is rotated more quickly than the tool which moves in the opposite direction over the item is rotated.
According to the invention, by simply rotating the tools which rotate in the direction like a roller faster than the tools which are rotated in the opposite direction, there can hereby be achieved a completely uniform sanding effect by all of the sanding segments regardless of their direction of rotation.
In a surprisingly simple manner, there is hereby achieved a completely perfect sanding result, completely without any variation in the sanding by the individual sanding tools, and with a completely uniform wear on the sanding elements as a result.
Moreover, a uniform physical loading of the item on the belt is achieved, in that there will be uniform side effects on the item from both the tools which rotate like a roller and those which rotate in the opposite direction.
To this can be added that in step with the wear, the speed of rotation of the sanding tools can gradually be increased to compensate for the reduced sanding effect while avoiding the hitherto-known simultaneous increase in non-uniformity in the sanding, which occurs particularly due to the increased heating-up of the sanding tools which rotate in the opposite direction. This is especially important for the sanding of metal plate, where variations in temperature will give rise to tensions and deformations in the metal plate.
As disclosed in claim
2
, by letting the tools which rotate in the direction like a roller rotate 13% faster than the tools rotating in the opposite direction, theoretically a completely uniform sanding pressure is achieved for both types of sanding tools, but since the centrifugal force plays a role at the relatively high speeds of rotation, an increase of only 7% in the speed of the tools rotating in the rolling direction has shown to provide the most uniform sanding result, and herewith a correspondingly uniform wear on the sanding elements.
Due to the progressiveness of the centrifugal force, the increase in rotation of 7% will correspond to the theoretical compensation of 13% for achieving a uniform sanding force or sanding pressure.
REFERENCES:
patent: 4646473 (1987-03-01), Hundebol
patent: 5131292 (1992-07-01), Hundebol
patent: 5274962 (1994-01-01), Hundebol
patent: 5291689 (1994-03-01), Hundebol
patent: 5441440 (1995-08-01), Hundebol
patent: 5601481 (1997-02-01), Hundebol
patent: 156703 (1989-09-01), None
patent: 165549 (1992-12-01), None
patent: 93 00243 Y6 (1993-12-01), None
patent: 0 320 558 (1987-12-01), None
patent: 0 458 724 A1 (1991-05-01), None
patent: 0 471 641 A2 (1991-08-01), None
patent: 2141648 (1985-01-01), None
patent: WO 91/17867 (1991-11-01), None
patent: WO 94/27781 (1994-12-01), None
patent: WO 98/05472 (1998-02-01), None
Banks Derris H.
Coleman Sudol Sapone PC
HH Patent A/S
Sapone William J.
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