ROUGHING DISC HAVING A BACKING LAYER

MEULE DE DEGROSSISSAGE COMPRENANT UNE COUCHE DE SUPPORT

English Abstract

The invention relates to a roughing disc for machining material surfaces, comprising a disc-shaped main body having a tool side, which can face a tool, and a workpiece side, which can face a workpiece, the main body comprising a central opening through which an axis of rotation passes and which serves for direct or indirect attachment of a drive shaft of the tool, a disc-shaped backing layer disposed on the tool side, at least one abrasive layer, and a separating layer between adjacent layers. The backing layer is made of a material mixture that is free of abrasive additives and that comprises at least one mineral additive.

French Abstract

L'invention concerne une meule de dégrossissage pour l'usinage de surfaces de matériau. La meule de dégrossissage comprend un corps de base en forme de disque pourvue d'une face outil pouvant être tournée vers un outil et d'une face pièce pouvant être tournée vers une pièce. Le corps de base comporte un évidement central traversé par un axe de rotation pour le raccordement direct ou indirect d'un arbre d'entraînement de l'outil, une couche de support en forme de disque agencée sur le côté outil, au moins une couche de dégrossissage et une couche de séparation entre les couches voisines. La couche de support est formée d'un mélange de matériau, lequel est exempt d'additifs abrasifs et lequel comporte au moins un additif minéral.

Claims

6
Claims
1. A roughing disc for machining material surfaces, comprising
a disc-shaped main body (3) having a tool side (13), which can face a tool,
and a work-
piece side (12), which can face a workpiece, the main body (3) comprising a
central
opening (2) through which an axis of rotation (5) passes and which serves for
direct or
indirect attachment of a drive shaft of the tool, a disc-shaped backing layer
(6) dis-
posed on the tool side (13), at least one abrasive layer (8a, 8b), and a
separating layer
between adjacent layers, characterized in that the backing layer (6) is made
of a mate-
rial mixture that is free of abrasive additives and that comprises at least
one mineral
additive.
2. The roughing disc according to claim 1, characterized in that the mineral
additive is
basalt, quartz sand, wollastonite, aluminum silicate and/or kaolin.
3. The roughing disc according to claim 1 or 2, characterized in that the
mineral additive
has a Mohs hardness of at least 2, preferably between 7 and 9.
4. The roughing disc according to any one of claims 1 to 3, characterized
in that the
mineral additive has a grain size of 30 to 1000 µm, preferably 200 to 500
µm.
5. The roughing disc according to any one of claims 1 to 4, characterized
in that the grain
of the mineral additive is covered in phenolic resin systems comprising a
resol/novolak
mixture.

7
6. The roughing disc according to claim 5, characterized in that the resol has
a viscosity
of 1000 to 5000 mPa.s, preferably 1200 to 3500 mPa.s.
7. The roughing disc according to claim 5 or 6, characterized in that the
novolak has a
hexamethylenetetramine content of at least 9 vol%, preferably 12 to 16 vol%,
and a
flow length of 15 to 35 mm, preferably 17 to 26 mm.
8. The roughing disc according to any one of claims 5 to 7, characterized
in that defined
amounts of other additives and/or aggregates of less than 20 vol% are
additionally add-
ed to the novolak.
9. The roughing disc according to any one of claims 1 to 8, characterized
in that the
separating layer is a glass fabric layer (10).

Description

CA 03033406 2019-02-08
PC T/EP2017/063090
KLINGSPOR AG M/KLI-072-WO
ROUGHING DISC HAVING A CARRIER LAYER
The invention relates to a roughing disc.
A roughing disc of this kind is known from the state of the art and is
suitable for rough-
grinding of material surfaces of various materials, i.e. for planar removal of
material. It
comprises a disc-shaped main body having a tool side, which can face a tool,
and a work-
piece side, which can face a workpiece. The main body comprises a central
opening
through which an axis of rotation passes and which serves for direct or
indirect attachment
of a drive shaft of a tool. The main body further comprises a disc-shaped
backing layer
disposed on the tool side, at least one abrasive layer, and a separating layer
between
adjacent layers.
Known roughing discs consist of multiple abrasive layers which comprise a
mixture of
phenolic resin and abrasive grains, wherein said mixture can be blended with
various fillers
and additives. It is also known for the layers to be separated from each other
by separating
layers, the abrasive layers and the separating layers being disposed
alternately along the
axis of rotation.
Also, roughing discs that have layers made of different materials are known.
This allows
precise adjustment to the application or to the grinding process through
different abrasive
mixtures in the various abrasive layers.
However, known roughing discs do not exhibit a satisfactory interconnection
between
adjacent layers made of different materials and the inserted glass fabric
layers. Moreover,
known roughing discs lack strength and/or rigidity.

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2
The object of the invention is to provide a roughing disc of the kind
mentioned above
which is characterized by an improved structure and which exhibits, in
particular, improved
interconnection between adjacent layers made of different materials and
improved strength
and/or rigidity.
According to the invention, this object is attained by the roughing disc
having the features
of claim 1.
The roughing disc according to the invention comprises a disc-shaped main body
having a
tool side, which can face a tool, and a workpiece side, which can face a
workpiece. The
main body comprises a central opening through which an axis of rotation passes
and which
serves for direct or indirect attachment of a drive shaft of the tool, a disc-
shaped backing
layer disposed on the tool side, at least one abrasive layer, and a separating
layer between
adjacent layers. As used here, the term adjacent layers refers to adjacent
abrasive layers in
an assembly of multiple abrasive layers and to an abrasive layer and a backing
layer
adjacent thereto. The roughing disc according to the invention is in
particular characterized
in that the backing layer is made of a material mixture that is free of
abrasive additives and
that comprises at least one mineral additive.
This ensures good interconnection between the backing layer, which does not
comprise any
abrasive additives, and the abrasive layer, which does comprise abrasive
additives. Moreo-
ver, good interconnection with the glass fabric and appropriate strength
and/or rigidity can
be ensured. The advantages of the roughing disc according to the invention are
achieved in
particular by the backing layer being free of abrasive additives and having a
purely support-
ing function. Mineral additives are particularly suitable to achieve said
function.
In a preferred embodiment of the roughing disc according to the invention, the
mineral
additive can be basalt, quartz sand, wollastonite, aluminum silicate and/or
kaolin. The
mixture of the at least one backing layer can also comprise different
additives from this
group.

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3
In another preferred embodiment of the roughing disc according to the
invention, the
mineral additive can have a Mohs hardness of at least 2, preferably between 7
and 9. This
in particular allows ensuring high strength of the roughing disc the higher
the hardness of
the additive is.
In another preferred embodiment of the roughing disc according to the
invention, the
mineral additive has a grain size of 30 to 1000 gm, preferably 200 to 500 gm.
In another preferred embodiment of the roughing disc according to the
invention, the grain
of the mineral additive is covered in phenolic resin systems comprising a
resol/novolak
mixture. Resols are meltable soluble phenolic plastics that contain reactive
methylol groups
and are obtained when phenols are condensed with formaldehyde under basic
conditions.
The benzene rings are connected via methylene groups and via ether bridges.
Novolaks are
phenolic resins having a formaldehyde/phenol ratio of less than 1:1 and are
obtained by
acidic condensation of the educts.
In another preferred embodiment of the roughing disc according to the
invention, the resol
has a viscosity of 1000 to 5000 mPa-s, preferably 1200 to 3500 mPa.s.
In another preferred embodiment of the roughing disc according to the
invention, the
novolak has a hexamethylenetetramine content of at least 9 vol%, preferably 12
to 16 vol%,
and a flow length of 15 to 35 mm, preferably 17 to 26 mm. Moreover, the
novolak can be
modified novolak.
In another preferred embodiment of the roughing disc according to the
invention, additional
defined amounts of other additives and/or aggregates of less than 20 vol% can
be added to
the novolak.
Other advantages and advantageous embodiments of the subject-matter of the
invention are
apparent from the description, the drawing, and the claims.

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4
An embodiment of a roughing disc according to the invention is illustrated in
a schemati-
cally simplified manner in the drawing and will be explained in more detail in
the following
description.
The single figure of the drawing shows a section through a roughing disc
according to the
invention.
Roughing disc 1 illustrated in the drawing has a disc-shaped main body 3
having a layered
structure and an outer radius a. Main body 3 has a tool side 13, which can
face a tool, and a
workpiece side 12, which can face a workpiece. Main body 3 comprises a central
opening 2
through which an axis of rotation 5 passes. Axis of rotation 5 is located in
the center of
rotation of roughing disc 1. An insert 4 for attaching roughing disc 1 to a
drive shaft of a
tool is disposed in opening 2. A backing layer 6 is disposed at tool side 13
of roughing disc
1, which faces the tool.
Backing layer 6 comprises a mixture that is free of abrasive additives and
that comprises at
lest one mineral additive. The mineral additive can be basalt, quartz sand,
wollastonite,
aluminum silicate and/or kaolin. The mixture of the at least one backing layer
can also
comprise different additives from this group. Moreover, the additive can have
a Mohs
hardness of at least 2, preferably between 7 and 9. The grain size of the
additive can be
between 30 and 1000 um, preferably between 200 to 500 um. The grains of the
additive
can be covered in phenolic resin systems, wherein the phenolic resin system
can comprise a
resol/novolak mixture. The resol can have a viscosity of 1000 to 5000 mPa.s,
preferably
1200 to 3500 mPa-s. The novolak can have a hexamethylenetetramine content of
at least
9 vol%, preferably 12 to 16 vol%, and a flow length of 15 to 35 mm, preferably
17 to
26 mm. Additionally, the novolak can comprise additional defined amounts of
other
additives and/or aggregates of less than 20 vol%. Thus, backing layer 6 has
high strength. It
can also comprise a mesh-like inlay in order to further increase the stability
of roughing
disc 1.
Moreover, roughing disc 1 has two abrasive layers 8a, 8b which are stacked in
the direction
of axis 5 and which are disposed on workpiece side 12. Abrasive layers 8a, 8b
can com-

CA 03033406 2019-02-08
prise abrasive grains, such as regular brown fused alumina and derivatives,
blue fired
alumina, white fused alumina, zirconia alumina, silicon carbide, ceramic
grain, pink fused
alumina, and/or monocrystalline alumina. Additionally, the abrasive layers can
comprise
supporting fillers, such as poly aluminum fluoride, cryolite, pyrite, calcite,
wollastonite,
5 and/or graphite, which can be bound by phenolic resin systems. Thus, a
phenolic-resin
abrasive grain mixture is formed, which can be blended with various fillers
and additives.
A separating layer, which is a glass fabric layer 10, is disposed between the
two abrasive
layers 8a, 8b. Another glass fabric layer 10 is disposed between backing layer
6 and
abrasive layer 8a adjacent to backing layer 6. Glass fabric layers 10 act as
separating layers
.. and serve the strength of roughing disc 1. Glass fabric layers 10 extend
from an outer edge
of roughing disc 1 to central opening 2 and surround central opening 2
annularly.
To ensure optimal connection to a tool, central opening 2 is realized as a
recessed hub.

Representative Drawing