GRINDING DEVICE

DISPOSITIF DE PONCAGE

English Abstract

The invention relates to a grinding device, comprising a support element (3) and a preferably flexible grinding means (5) held thereon, which has a carrier resting against the support element (3), and a grinding layer designed in such a way that in a grinding position, the grinding means (5) is held on the support element (3) in a frictionally locking manner.

French Abstract

L'invention concerne un dispositif de ponçage comprenant un élément d'appui (3) et un agent abrasif (5) de préférence flexible maintenu sur celui-ci, qui est constitué d'un support reposant sur l'élément d'appui (3) et d'une couche abrasive. Le dispositif de ponçage est réalisé de telle sorte que l'agent abrasif (5) est maintenu dans la position de ponçage par friction sur l'élément d'appui (3).

Claims

CA 03107230 2021-01-21
7
Claims
1. Grinding device comprising a support element (3) and a
preferably flexible grinding means (5) held thereon, said
grinding means consisting of a carrier, which bears against a
closed surface of the support element (3), and a grinding layer,
characterized in that the grinding means (5), the surface of the
carrier of which facing towards the support element (3) is
structured, is held against the support element (3) by
frictional engagement across the entire surface in the grinding
position, wherein the coefficient of friction of the support
element (3)/grinding means (5) pairing is between 0.2 and 0.5.
2. Grinding device according to claim 1, characterized in that
the friction force generated by pressing the support element (3)
against the grinding means (5) is between 0.5 to 2.0 N/mm2.
3. Grinding device according to claim 1 or 2, characterized
in that the side of the carrier facing towards the support
element (3) is made of a polymer, of an elastomer or of leather.
4. Grinding device according to any one of the preceding
claims, characterized in that the thickness of the carrier on
the side facing towards the support element (3) is between 0.7
and 4 mm.
5. Grinding device according to any one of the preceding
claims, characterized in that the surface of the carrier facing
towards the support element (3) is made of a foam.
6. Grinding device according to any one of the preceding
claims, characterized in that the grinding means (5) is designed
as a grinding belt.
Date Regue/Date Received 2021-01-21

Description

CA 03107230 2021-01-21
PCT/EP2019/073205
Grinding device
The invention relates to a grinding device according to the
preamble of claim 1, and to a grinding means.
Such grinding devices consist of a shape-stable support element
which may be in the form of a support disc or in the form of a
grinding block, the latter in the case of manual use.
The grinding means is in the form of a flexible grinding sheet
or a grinding belt, which is held on the support element by
means of a hook-and-loop connection, for which purpose the
support element/grinding means pairing has suitably designed
hook-and-loop layers.
In the case of the grinding means, this is provided on the side
of a carrier that is located opposite a grinding layer, which
consists of an abrasive grit, it being possible for the carrier
to be made of paper, film, fabric, or a combination thereof.
In addition to this hook-and-loop connection, which establishes
a form fit, it is proposed in DE 10 2017 108 191, which was not
previously published, to hold the grinding means on the support
element, i.e. a support disc, by means of a material bond, by
means of a form fit or by frictional engagement, the frictional
engagement being established by sucking the grinding means onto
the support disc.
The material bond takes place by adhesion, wherein the contact
surface of the carrier that makes contact with the support disc
is equipped with a self-adhesive layer.
However, the known connections of the grinding means to the
support element are disadvantageous in some respects, in
particular with regard to handling, but also with regard to
relatively cost-intensive production.
Date Recue/Date Received 2021-01-21

CA 03107230 2021-01-21
2
For instance, the construction of the carrier for providing the
hook-and-loop or self-adhesive layer is cost-intensive, in
particular since such a layer has to be formed in multiple
stages. In addition, they are subject to a relatively high degree
of wear due to the connection being made and released.
The holding of the grinding means on the support element by
means of vacuum requires special measures with regard to the air
permeability and sealing. This means that the support disc must
have apertures, through which air is sucked in order to hold the
grinding means thereon.
The handling when equipping the grinding device with grinding
means is also sometimes quite awkward and stands in the way of
optimized use, in particular with regard to changeover times.
This applies equally to a grinding device as discussed in DE 10
2010 001 769 Al, in which frictional engagement between the
support element and the grinding means is achieved in that the
support element is provided with bristles on the side thereof
facing towards the grinding means, which bristles engage in a
necessarily porous surface of the carrier.
The disadvantage with this is that the carrier is permeable, as
a result of which grinding dust enters the area of connection
to the support element, which leads to considerable problems as
the operating time increases.
US 3 345 785 A discloses a grinding device with the suggestion
of a frictional connection between a flexible support element
and a grinding means, wherein the friction fit is established
between a peripheral flange of the grinding means and the support
element.
The problem addressed by the invention is that of further
developing a grinding device and a grinding means of the generic
type in such a way that it can be produced more easily and cost-
effectively and it is easier to handle.
Date Recue/Date Received 2021-01-21

CA 03107230 2021-01-21
3
This problem is solved by a grinding device having the features
of claim 1.
Firstly, it is crucial that the coefficient of friction between
the support element and the grinding means, which is held thereon
across the entire surface, is sufficient to absorb the
longitudinal and transverse forces that occur during grinding,
wherein according to the invention the coefficient of friction
of the pairing is between 0.2 and 0.5.
As has been found, such a coefficient of friction is sufficient
in particular when grinding a finished surface at certain
points, wherein the friction force between the support disc and
the grinding means is generated by pressure when the grinding
device, i.e. the support element and the grinding means, is
pressed onto the surface to be treated. This friction force is
preferably between 0.5 to 2.0 N/mm2.
As long as the friction force is greater than the counterforce
produced by the grinding process, mutual displacement of the
support element and grinding means is prevented. Given the
appropriate coefficient of friction of the pairing, grinding
across a surface is possible without any problem, wherein the
grinding means is designed to be flexible in the same way as in
the case of point grinding.
The grinding means, which may be in the form of a single sheet
or a grinding belt, consists of a carrier and a grinding layer
held thereon. While the carrier, which forms a contact layer to
the support element, is constructed in multiple stages in the
prior art and is designed in particular for a hook-and-loop or
adhesive connection, the carrier according to the invention is
produced as a single layer made of a suitable plastic, which
should be both elastic and flexible.
Polymers, elastomers or leathers are particularly suitable for
this, the thickness of the carrier being between 0.7 and 4 mm.
Date Recue/Date Received 2021-01-21

CA 03107230 2021-01-21
4
As mentioned, due to the flexible and elastic nature of the
carrier, the grinding of both flat and curved surfaces is
possible, the curved surfaces being convex or concave.
As has surprisingly been found, the frictional connection
between the support element and the grinding means is
particularly advantageous when the grinding means is in web
form. Since the grinding belt is precisely aligned and guided
in the area of connection to the support element, problem-free
positioning between the support element and the grinding sheet
is ensured.
The grinding belt is lifted off for moving the support element
to the next position, or the grinding belt slides away from the
support disc when the lifting or tearing force with which the
grinding belt is detached from the support element is greater
than the friction force between the support element and the
grinding belt.
In a manner known per se, the grinding itself takes place, as
mentioned, at certain points or across a surface, using orbital,
rotating or vibrating movements.
Instead of the aforementioned one-piece construction of the
carrier, there is also the possibility of multi-piece
construction. By way of example, the carrier which carries the
grinding means may be made of paper, while the contact surface
which bears against the support element is made of an
elastomeric, rubber-like or leather material.
Particularly if the surface of the carrier is smooth, for example
in the form of a film, the surface assigned to the support
element is slightly structured and is likewise formed of an
elastomeric, rubber-like or leather material.
The rough surface of the carrier formed of a fabric is slightly
structured on the side held by frictional engagement on the
Date Recue/Date Received 2021-01-21

CA 03107230 2021-01-21
support element and is possibly formed of a foam. For the
pairings mentioned, additional anti-slip means are not
absolutely necessary.
In any case, account should be taken of the fact that the
surfaces may be dry, moist or wet, with a corresponding effect
on the friction pairs.
Further advantageous embodiments of the invention are
characterized in the dependent claims.
One exemplary embodiment of the invention will be described
below with reference to the accompanying drawing.
The single figure shows a grinding device according to the
invention in a schematic side view.
The figure shows a grinding device 1 for removing a flaw in a
surface, in particular a finished surface, of an object (not
shown) by grinding.
This grinding device 1 has a robot arm 2 and a support element
3 held thereon in the form of a support disc, which support
element is movable, for example in an orbital, vibrating or
rotating manner, relative to the surface in order to grind the
flaw.
In the grinding position, i.e. in contact with the surface of
the object, as shown in the figure, a grinding means 5, in the
example in the form of a grinding belt, bears with frictional
engagement against the support element 3, wherein the rear side
of the grinding means 5, so to speak, which bears against the
support element 3, is designed as a carrier which on the other
side carries an abrasive grit that makes contact with the surface
of the object.
The grinding means 5 is held in a dispenser in the form of a
cassette 4 and is wound as a roll 6 on an unwinding shaft 7, and
Date Recue/Date Received 2021-01-21

CA 03107230 2021-01-21
6
is wound onto a winding shaft 8, preferably in cycles, in a
manner corresponding to the grinding process.
The frictional engagement between the support element 3 and the
grinding means 5 is released by lifting the support element 3,
so that the grinding means 5 can be advanced without hindrance.
Date Recue/Date Received 2021-01-21

Representative Drawing