Abrading – Accessory
Reexamination Certificate
2001-04-03
2003-08-19
Rose, Robert A. (Department: 3723)
Abrading
Accessory
C451S539000
Reexamination Certificate
active
06607429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a support for temporary fixation of a self-sticking abrasive and/or polishing sheet which includes an adhesive layer. The support includes a support surface onto which the self-sticking sheet can be applied.
2. The Prior Art
In the art of materialography (the study of materials, e.g. metals; metallography) it is common practice to grind and/or polish the samples before performing the various analysis on them. For most analyses, it is crucial that the surface of the sample to be analyzed is as smooth as possible.
Accordingly, a great number of abrasive and polishing means, e.g., in terms of abrasive sheets having various grinding grain sizes, are used. The treatment of a materialographic sample normally starts with an abrasive sheet having a relatively large grain size and eventually ends up with an abrasive sheet having a very small grain size and/or a polishing cloth, the process including a number of treatment steps using means each having different and gradually reduced grain sizes. It is therefore crucial that the changing of the abrasive and/or polishing sheet is as simple and easy as possible. Furthermore, it is desirable that the reuse of an abrasive and/or polishing sheet which is not worn out is facilitated.
It is known in the art of polishing and/or grinding to use abrasive or polishing sheets having a frontal face for treating the sample and comprising a layer of adhesive on the backside in order to fixate the sheet temporarily to a rotatable and/or otherwise movable abutment of a grinding and polishing apparatus during the abrasion or polishing process.
These self-sticking abrasives and/or polishing sheets are also widely used for preparing materialographic samples, where they are adhered directly to the normally rotatable abutment of a grinding and polishing apparatus.
However, it is generally the case that the adhesive force between the commonly used sheets and the ordinary abutment of a typical grinding and polishing apparatus is rather strong, and consequently the removal of the sheet becomes very troublesome. Furthermore, it is thus very common that the sheet will become wrinkled or torn during removal and accordingly completely unsuited for reuse which is an otherwise desirable option in case the sheet is not completely worn out.
EP 2 750 354 discloses a rotatable abutment in a grinding and/or polishing machine. At the side facing the abrasive or polishing sheet the abutment comprises a coating of a material which is softer than the material used for the platter itself. As an example of a material suitable as coating polytetrafluoruethylene (Teflon®) is mentioned. The coating should facilitate the removal of used or wrongly mounted abrasive or polishing sheets from the abutment.
Thus EP 2 750 354 teaches a way of lowering the adhesive force by introducing a surface of a releasing material. However, if the adhesive force is reduced too much, the sheet will be displaced during use which could result in severe damage to the sample, the machinery and/or even injury on the operating personal.
Accordingly, there persists a need for a solution to the problem of fulfilling the apparently mutually exclusive objectives of securing the commonly used self-sticking abrasive or polishing sheets to the movable abutment, while at the same time making it easy to remove the sheets after use and in a manner which does not damage the sheets which are not completely worn out.
SUMMARY OF THE INVENTION
This object is achieved by the support according to the invention which has the property that the surface of the support is so adapted that when a self-sticking abrasive or polishing sheets is applied to the support surface, the resulting adhesive force between the sheet and the support surface is varied over the surface of the support.
The invention also relates to a support in combination with a self-sticking abrasive or polishing sheets.
The term support as used herein designates an integral part of an abutment or an adapter adapted to be placed on an abutment, optionally temporarily placed on an abutment.
The support comprises a generally planar support surface area onto which a self-sticking abrasive or polishing sheets can be adhered. The term “generally planar support surface” means that the surface may contain small irregularities such as small protrusions or cavities, provided that the irregularities do not prevent a self-sticking abrasive or polishing sheets to be adhered to the surface, and to remain adheared during use of the abutment containing said support, in a polishing or abrasion process.
The support surface is defined by an outer periphery, this periphery normally is a border line to an outer area of the support, said outer area forms an angle with said support surface.
The self-sticking abrasive or polishing sheets, also designated “grinding sheet” may be of any conventional type comprising a first side (front face)having an abrasive or polishing layer, and a second side (back side) totally or partly covered with an adhesive.
The invention is based on the surprising recognition that only a part of the abrasive sheet needs be strongly adhered to the movable support in order to ensure a secure fixation. When the contact area exhibiting strong adhesion is reduced, the ease of dismounting of the sheet is significantly increased. However, even though only a part of said contact area remains, a surprisingly large amount of the sheet's ability to stay fixed during use is intact.
It is believed that this advantageous effect is at least partly due to the fact that the forces, which prevent the sheet from being displaced during use, work in a direction parallel with the surface plane of the sheet whereas the forces keeping the sheet to the abutment during dismounting are substantially perpendicular to said plane. It has surprisingly been found that the two forces depend differently on the size of the contact area exhibiting strong adhesion, i.e. the force necessary for dismounting the sheet is reduced relatively more than the force needed for displacing the sheet during use, when the contact area exhibiting strong adhesion is reduced.
According to the invention, it is thus possible to meet the objective of facilitating the dismounting and reuse of abrasive and/or polishing sheets from a movable abutment while at the same time substantially maintaining all other properties, i.e. the safety during use and the quality of the abrasion and/or polishing process. According to the basic invention, this is accomplished by manipulating the adhesive force between the sheet and the abutment in a manner so that the force varies from the edges to the centre of the sheet. Furthermore, it is an advantage that any conventional abrasive and/or polishing sheets may be used together with the support according to the invention.
Although the support surface of the support, according to the invention, in principle can have any shape, e.g. square, triangular or circular, most grinding and/or polishing apparatus for use in the art of materialography have rotatable circular abutments, and thus it is highly preferable that the support surface of the support according to the invention is circular. Accordingly, the adhesive force is preferably varied in radial direction of the circular support surface. By the term “radial direction” means the direction from the centre to the periphery of the support surface.
The support surface of the support, according to the invention at least two subareas having different surface tension, whereby the adhesive force between said subareas and a abrasive and/or polishing sheet applied onto said support surface, differs from each other.
A subarea of the support surface means a segment or a zone of the support surface, which segment or zone may have any size and shape. The support surface may e.g. comprise a number of discrete zones, which zones each has a surface tension different from each other. In another embodiment the support surface may have a number of discrete zones plac
Dykema Gossett PLLC
Rose Robert A.
Struers A/S
LandOfFree
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