U.S. patent application number 11/762969 was filed with the patent office on 2007-12-20 for die-cutting method, flexible abrasive product and apparatus for manufacturing thereof.
This patent application is currently assigned to Oy KWH Mirka Ab. Invention is credited to Goran Johannes Hoglund.
Application Number | 20070293131 11/762969 |
Document ID | / |
Family ID | 36651516 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070293131 |
Kind Code |
A1 |
Hoglund; Goran Johannes |
December 20, 2007 |
DIE-CUTTING METHOD, FLEXIBLE ABRASIVE PRODUCT AND APPARATUS FOR
MANUFACTURING THEREOF
Abstract
The present invention relates to a method for manufacturing a
flexible abrasive product, to such an abrasive product as well as
to an apparatus for manufacturing the same. Hereby, the abrasive
product is formed to be of the shape of a substantially regular
polygon by die cutting it off a material strip. In the present
case, the abrasive product has obtained a polygonal shape in which
adjacent sides have a reciprocal interior angle of substantially
120 to 150.degree., whereby the die cutting is carried out in such
a way that it coincides at least partly with the die cutting of
several adjacent abrasive products. In this way, the die cutting
can provide a partially continuous cutting line on the periphery of
each individual abrasive product, which cutting line has a
significant part of its length in common with the adjacent abrasive
products.
Inventors: |
Hoglund; Goran Johannes;
(Nykarleby, FI) |
Correspondence
Address: |
ALTERA LAW GROUP, LLC
6500 CITY WEST PARKWAY
SUITE 100
MINNEAPOLIS
MN
55344-7704
US
|
Assignee: |
Oy KWH Mirka Ab
Jeppo
FI
|
Family ID: |
36651516 |
Appl. No.: |
11/762969 |
Filed: |
June 14, 2007 |
Current U.S.
Class: |
451/533 |
Current CPC
Class: |
B24D 11/008
20130101 |
Class at
Publication: |
451/533 |
International
Class: |
B24D 11/00 20060101
B24D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 19, 2006 |
FI |
20065421 |
Claims
1. A method for manufacturing a flexible abrasive product, which
comprises a flexible backing, at least one glue layer on one side
of the backing and a layer of abrasive agent bonded thereto by the
glue layer, which abrasive product is formed to be of a shape of a
substantially regular polygon by die cutting a material strip,
characterized by giving the abrasive product a polygonal shape in
which adjacent sides have a reciprocal interior angle of
substantially 120 to 150.degree. in such a way that the die cutting
is carried out such that it coincides at least partly with the die
cutting of several adjacent abrasive products, whereby a partially
continuous cutting line is provided in the die cutting on the
periphery of each individual abrasive product, which cuffing line
has a significant part of its length in common with adjacent
abrasive products.
2. A method for manufacturing a flexible abrasive product according
to claim 1, wherein in the manufacture of an octagonal abrasive
product a peripheral cutting line is obtained that is common to the
extent of 3/8.
3. A method for manufacturing a flexible abrasive product according
to claim 1, wherein in the manufacture of a hexagonal or
dodecagonal abrasive product a peripheral cutting line is obtained
that coincides with six of the sides.
4. A method for manufacturing a flexible abrasive product according
to claim 1, wherein the die cutting takes place at two or three
stages.
5. A method for manufacturing a flexible abrasive product according
to claim 4, wherein the die cutting takes place at work stages
following each other successively.
6. A method for manufacturing a flexible abrasive product according
to claim 5, wherein the die cutting takes place with two die
cutting elements arranged to provide a cutting line on the sides of
the polygon in such a way that in the first die cutting stage the
common cutting lines are preferably left partially uncut in the
transportation direction of the material strip, as is also at least
one of the common cutting lines in the cross direction of the
material strip, in order to maintain tension and shape in the
material strip until the second die cutting, in which the abrasive
product is finally detached from the material strip.
7. A method for manufacturing a flexible abrasive product according
to claim 4 wherein dust extraction openings are formed in the
abrasive product at the first die cutting stage.
8. A method for manufacturing a flexible abrasive product according
to claim 1, wherein the die cutting takes place with blades such
that crossing cutting lines somewhat overlap each other.
9. A method for manufacturing a flexible abrasive product according
to claim 1, wherein rows of successive abrasive products are formed
in a material strip but are left therein not completely loose from
each other, the abrasive products thus forming a continuous chain
via connecting parts between them, the abrasive products being
subsequently packed.
10. A method for manufacturing a flexible abrasive product
according to claim 9, wherein the connecting part between
successive abrasion products comprising, in the forming of a
continuous chain of abrasive products, a shared tear line weakened
by the die cutting in such a way that the abrasive products can be
easily detached from each other.
11. A flexible abrasive product, which comprises a flexible
backing, at least one glue layer on one side of the backing and a
layer of abrasive agent bonded thereto by the glue layer, which
abrasive product is of a shape of a substantially regular polygon
and is die cut off a material strip, characterized in that the
abrasive product has an even number of sides, whereby the polygonal
shape encompasses abrasive products whose adjacent sides have a
reciprocal interior angle of substantially 120 to 150.degree..
12. A flexible abrasive product according to claim 11, wherein the
number of sides is six.
13. A flexible abrasive product according to claim 11, wherein the
number of sides is eight.
14. A flexible abrasive product according to claim 11, wherein the
number of sides is twelve.
15. A flexible abrasive product according to claim 11, wherein the
abrasive product has dust extraction openings.
16. An apparatus for manufacturing a flexible abrasive product,
which abrasive product comprises a flexible backing, at least one
glue layer on one side of the backing and a layer of abrasive agent
bonded thereto by the glue layer, which abrasive product is
arranged to be detached from a material strip with a die cutting
tool, characterized in that the structure of the die cutting tool
comprises blades arranged to generate substantially rectilinear
cutting lines, whereby the blades are arranged to generate a
cutting line which, when completed, is of the shape of a
polygon.
17. An apparatus for manufacturing a flexible abrasive product
according to claim 16, wherein the blades are divided to at least
two successive die cutting elements.
18. An apparatus for manufacturing a flexible abrasive product
according to claim 16, wherein the die cuffing tool comprises
blades arranged to provide cutting lines which somewhat overlap
each other.
19. An apparatus for manufacturing a flexible abrasive product
claim 16, wherein the die cutting tool comprises die cutting means
for forming dust extraction openings in the abrasive product.
Description
BACKGROUND
[0001] The present invention relates to a method for manufacturing
a flexible abrasive product of the kind presented in the preamble
of claim 1. The invention further relates to a flexible abrasive
product of the kind presented in the preamble of claim 11, as well
as to an apparatus of the kind presented in the preamble of claim
16, intended for manufacturing such a flexible abrasive
product.
[0002] In particular, the invention relates to what is called
flexible abrasive and polishing discs used in rotating and
oscillating work stages.
PRIOR ART
[0003] In die cutting various abrasive products, for example discs,
a narrow material bridge is normally left over which binds together
the waste material remaining between the die cut abrasive products.
Thanks to such a material bridge, the waste material forms a
continuous web that is easier to gather and remove from the
die-cutting tool. On the other hand, such material bridges also
bring about extra waste and affect thus not only the output of the
material strip but also the handling of the waste material. The
significant amount of waste material also has a negative effect on
the price of the abrasive product, and the costs of the waste
material handling rise
[0004] There have been attempts to decrease this waste material by
placing the abrasive products to be die cut adjacent to each other
to save material. It has, however, turned out that when attempting
to cause two adjacent blades of a die-cutting tool to touch each
other, or at least to reduce the material bridge between the
abrasive products to a minimal string, the material strip will be
wedged in between the blades of the die-cutting tool in the area
where the blades are adjacent to each other. The blades must have a
given thickness and their cutting edge has been shaped conical in
the sharpening, due to which there is no inclination either on the
abrasive product side or on the waste material side of the
blade.
[0005] Die cutting flexible abrasive material is also difficult to
carry out in a purely technical sense. There are several different
reasons for this. First and foremost, the abrasive grains in the
material strip quickly wear the die-cutting tool used for the work
and make them blunt. The work requires thus continuous supervision
and maintenance of the die-cutting tools.
[0006] Secondly, the backside of the material strip usually has a
fastening layer of some kind. The fastening layer comprises either
self-adhesive glue, velour cloth with loops, attached with glue, or
loops of fiber integrated into the base material of the material
strip. In the die cutting carried out to detach the abrasive
product from the material strip, the loops, the self-adhesive glue
as well as the protective film applied against the self-adhesive
glue make the die cutting more difficult, because the remainders of
the die cutting stick to the fastening layer and the material strip
tends to stick to the die-cutting tool. Furthermore, it is very
difficult to succeed in cutting off all tough fibers which the
loops in the velour cloth is formed of or which the fibers
integrated into the material strip generate, particularly because
the die-cutting tools get blunt quickly due to the abrasive
grains.
[0007] It is also difficult to place abrasive products close to
each other, because it is purely generally difficult to obtain a
pure cut in die cutting if another cuffing line is touched with far
too small an angle. Herein lies a risk that the material strip will
bend and the completion of the die cutting will be prevented.
[0008] Die cutting of the abrasive material is further made more
difficult by the fact that the abrasive material must often also be
provided with dust extraction openings, die cut on the surface of
the abrasive material and divided more or less regularly thereto.
There are often several dust extract openings, and they have a
relatively small diameter. These dust extract openings are obtained
with particular capsular punching means, i.e. what are called tube
punchers, or by a type of cutting where a piston-shaped die-cutting
means cooperates with an opening in the opposite cutting plate.
Since the intention is to have clearance Inside the die-cutting
means that cuts the dust extract opening, the tube puncher is
structurally made substantially conical, whereby the abrasive
product to be die cut tends get stuck to the surface of the
die-cutting means because it is simultaneously cut loose from its
place in the continuous material strip.
DEFINITION OF THE PROBLEM
[0009] With the present invention, the problems of known solutions
can be substantially avoided. By applying the invention, waste
material can be significantly decreased in manufacturing flexible
abrasive products, at the same time as reliable die cutting with
minimal defects is achieved.
[0010] This object is achieved in accordance with the invention by
giving the method for manufacturing a flexible abrasive product the
characterizing features of the characterizing part of claim 1. The
flexible abrasive product is given the characterizing features of
the characterizing part of claim 11, while the apparatus for
manufacturing of such a flexible abrasive product is given the
characterizing features of the characterizing part of claim 16.
[0011] The corresponding dependent claims that follow present
suitable further embodiments and variations of the invention that
further improve the functioning of the invention.
[0012] The invention is based on the idea that the amount of waste
material can be reduced by deviating from the conventional circular
shape of abrasive products used in rotating work stages, and by
making the abrasive product polygonal instead, for example
hexagonal, octagonal or dodecagonal. The greater the diameter of
the abrasive product, the more corners may preferably be given to
the product.
[0013] Thanks to the polygonal shaping, adjacent abrasive products
can have common cuffing lines.
[0014] In the present invention, the "blade" refers to the working
part of a cutting means, performing the cutting work. This blade
provides hereby a "cutting line" in the material strip.
[0015] With the present invention, several significant advantages
over the prior art are achieved. Hence, it is possible to reduce
not only the amount of waste material but also the total length of
the required cutting line by enabling the adjacent abrasive
products to have common cutting lines.
[0016] This can be illustrated with a dodecagon. When placing
abrasive products shaped as dodecagons in such a way that they abut
on each other, they have half of the 12 sides in common with one of
the adjacent dodecagons. This means that the total cutting line is
reduced by 25%.
[0017] By deviating from the circular cutting line and replacing it
with a broken line it is possible, at the same time, to increase
the angle at the points where the cutting lines touch each other
and to ensure clean cuts in the die cutting. In this way, bending
of the material strip edge in the completion of the die cutting is
avoided. In the die cutting of for example the above-mentioned
dodecagons placed adjacent to each other, the intersection angle
between the blades, where thy touch each other, is either 30 or 60
degrees, which is enough to obtain a clean cut as far as to the
touching point of the out.
[0018] The die cutting of abrasive products can be simply improved
further by dividing the die cutting process into two or more steps
succeeding each other.
[0019] If the simpler angular geometry of the abrasive product is
hereby combined with cuffing at the first die-cutting stage both
possible dust extract openings in the abrasive product and
principally those edges that are directed more in the feed
direction of the material strip, the sticking of the abrasive
product to the tube punchers is prevented, because the abrasive
product still remains attached to the material strip. At the
following die-cutting stage or feed position, the remaining
continuous material bridges are cut off, whereby the abrasive
product is cut out and detached. In practice, the whole material
strip ceases to exist because the abrasive products have a large
number of common edges, and the minimal geometric waste there is
between, for example, dodecagonal abrasive products turn into
separate loose pieces that can be sucked away with underpressure or
that can drop into a collecting container where they are brought
about.
[0020] The die-cutting tool does not need to be formed as a single
piece either but can easily be divided into two or more parts
because of the simple geometric shape. The geometric structure of
the die-cutting tool is very simple and may preferably comprise
straight blade parts and possible tube punchers or other punching
tools.
[0021] Handling the finished abrasive products and possible waste
material also gets simpler in die cutting with several parts. Thus,
in the completion stage of the die cutting, the abrasive product
can be gripped with a receiving apparatus before the abrasive
product is completely detached from the material strip.
Subsequently, the abrasive disc fixed to the receiving apparatus is
cut off the material strip, so that it can be immediately after
this transported to further treatment or other handling.
[0022] Further advantages and details of the invention become
apparent from the description below.
BRIEF DESCRIPTION OF THE FIGURES
[0023] In the following, the invention is described in greater
detail with reference to the drawing, in which
[0024] FIG. 1 shows part of a material strip, indicating the
cutting lines for hexagonal abrasive products;
[0025] FIG. 2 shows part of a material strip, indicating the
cutting lines for octagonal abrasive products;
[0026] FIG. 3 shows part of a material strip, indicating the
cutting lines for dodecagonal abrasive products;
[0027] FIG. 4 show examples of a die-cutting sequence in
manufacturing a hexagonal abrasive product;
[0028] FIG. 5 show examples of a die-cutting sequence in
manufacturing an octagonal abrasive product; and
[0029] FIG. 6 show examples of a die-cutting sequence in
manufacturing a dodecagonal abrasive product.
PREFERRED EMBODIMENTS
[0030] Some preferred embodiments of the present abrasive product,
as well as the method and apparatuses for manufacturing thereof are
described in the following with reference to the above figures.
Hereby, the solution comprises the structural parts of the figures,
each of which is denoted with a reference numeral corresponding to
the reference numerals in the following description.
[0031] The figures thus show a flexible abrasive product, which is
particularly intended for rotating and/or oscillating abrasion. The
abrasive product comprises a flexible backing, to which a layer of
abrasive agent is bonded with at least one glue layer on one side
of the backing. On the opposite side of the abrasive agent, the
abrasive product preferably has a fastening layer in the form of a
glue layer, for example. The fastening layer can also comprise a
velour layer or loops applied to the backing to contribute to
Velcro fastening.
[0032] Such abrasive products are usually manufactured by die
cutting them out of a particular material strip 1 with one or more
die cutting tools, whereby the abrasive product 2 is both detached
from the material strip and provided with possible dust extract
openings 3. As can be seen from the attached figures, the present
abrasive product is a polygon. Preferably, it is a regular polygon
with an even number of sides. The polygon shape encompasses
particularly abrasive products whose adjacent sides have a
reciprocal interior angle of substantially 120 to 150.degree.,
whereby the number of corners is for instance 6, 8 or 12, which
also corresponds to the geometric shapes hexagon, octagon and
dodecagon. Distribution of a hexagonal abrasive product in the
material strip is schematically shown in FIG. 1, while distribution
of an octagonal abrasive product is shown in FIG. 2 and of a
dodecagonal abrasive product in FIG. 3. Naturally, the magnitude of
the interior angle or the number of corners of the polygon may be
greater than in the above example.
[0033] A dodecagonal version can in fact be considered a hexagonal
one in which the corners have been cut off. It means that there may
be versions that are dodecagons where every other side is shorter
than the six sides that are shared with the adjacent abrasive
product. The symmetry is then only hexagonal. If one goes as far as
to 16-angled products, the advantage of the shared cutting line
decreases, and also the intersection angle decreases. Thus, when
one approaches the circular shape, the effect of the idea is
significantly deteriorated.
[0034] When implementing the die cutting of the abrasive products 2
in accordance with FIGS. 1 to 3 in such a way that the die cutting
provides a partially continuous cutting line 4 on the periphery of
each individual abrasive product, at least part of the sides of
adjacent abrasive products meet. Such shaping in the die cutting
minimizes the total extension of the cutting lines and maximizes
the use of the material strip, still creating an abrasive product
that is well applicable to rotating and/or oscillating
abrasion.
[0035] For the most part, the cutting line obtained in the die
cutting is substantially rectilinear, whereby its total length is
less than the length of the cutting line in a conventional circular
abrasion disc, but in special cases the sides that are not shared
may be bent. As an example, the side of the polygon is
substantially of the shape of a circular line with a diameter
greater than the nut-formed perimeter of the shared sides, for
example equal to the diameter of the circumscribed circle of the
polygon
[0036] Thus, an abrasive product 2 is formed which is of the shape
of a substantially regular polygon by means of die cutting in such
a way that the die cutting at least partly coincides with the die
cutting of several adjacent abrasive products. Selecting the shape
of the abrasive product to be hexagonal or dodecagonal provides a
die cutting method where six of the sides are always shared. This
means that in the die cutting of a hexagonal abrasive product a
utilization degree of nearly 100% is achieved for the material
strip. If, on the other hand, octagonal abrasive products are die
cut, about 1/7 of the total length of the sides is shared.
[0037] To simplify the work process and to facilitate the handling
of the abrasive products 2 with the die cutting completed, the die
cutting may take place in two or more strokes, preferably in such a
way that the die cutting takes place in two successive work stages.
By die cutting at the first stroke both possible dust extract
openings 3 in the abrasive product and, for the most part, those
edges that are directed more in the feed direction of the material
strip, a continuous material strip is maintained at the same time
as the abrasive product is prevented from sticking to the tube
punchers or corresponding die cutting means used in shaping dust
extract openings. Since the abrasive product partially sticks to
the common material strip, it is prevented from getting stuck in
the die cutting means and being carried along with it.
[0038] At the following stage of the die cutting, i.e. in the feed
position, the remaining material bridges joining the abrasive
product 2 to the material strip 1 are cut off, which results in the
abrasive product being cut out and detached completely from the
surrounding material. In practice, it can be said that the whole
material strip ceases to exist. This is because the abrasive
products and the possible minimal geometric waste 5 between the
abrasive products turn into separate loose pieces without any
connecting material bridges. Subsequently, the waste material can
be sucked out with underpressure, or it can drop into a collecting
container where the waste material is brought about.
[0039] The die cutting can also be explained with reference to the
different abrasive products 2 in FIGS. 3 to 6. Thus, the material
strip 1 is, by way of example, arranged to feed forward exactly the
length of an abrasive product at every die cutting stroke. The
die-cutting tool is thus divided to two work stages in such a way
that it has, at its first work stage, blades that in the
transportation direction (to the left in the figure) cut, for the
most part, the longitudinal but also partially slanting sides in
the abrasive product. These blades are illustrated in FIGS. 4 to 6
by blades 6 in row 1, column 1.
[0040] At the same time, possible punching of dust extract openings
3 of the abrasive product with blades 8 takes place in the form of
tube punchers, for instance. These dust extract openings may
represent any types of hole forms and hole standards. It is simple
to die cut most different dust extract openings because the present
die cutting with several strokes makes the die cutting easier.
[0041] At the second work stage die cutting of the remaining sides
of the abrasive product takes place to cut the abrasive product 2
out completely. These blades 7 are, in turn, illustrated in FIGS. 4
to 6 by the blade on row 1, column 5.
[0042] The centre of the die cutting tool used at the second stage
of the die-cutting is placed in a die cutting head at a distance
from the centre of that part of the die-cutting tool which is used
at the first stage of the die cutting, which is equal to or a
multiple of the length of the abrasive product 2 in the
transportation direction of the material strip 1. Therefore, the
double length of the abrasive product is shown in the present
figure. The two work stages are naturally successively after each
other in the transportation direction of the material strip.
[0043] Division of the blades to adjacent rows is shown in rows 3
and 4, while the joint operation of the following work stages can
be seen in rows 7 and 8.
[0044] To ensure that the abrasive product 2 is always detached
from the material strip 1, the die cutting takes place with blades
where adjacent or crossing cutting lines 4 somewhat overlap each
other. Since the extent of such overlapping is insignificant, this
will not, by any means, affect the use of the abrasive product.
[0045] In FIGS. 5 and 6, it can also be seen that the cutting line
4 required for detaching a side of the abrasive product can be
generated by a blade divided into several parts. In this way,
critical corner points are avoided in the die cutting, and instead,
controlled overlapping with a complete cutting line is obtained as
a result.
[0046] The die cutting sequences and blade divisions presented in
FIGS. 4 to 6 are naturally only examples of different ways to carry
out the die cutting. The blades can be divided also in other ways
to achieve the desired result.
[0047] On the other hand, there are occasions when it is not
desirable to detach the abrasive products 2 completely from each
other. In such situations, the abrasive products are shaped to form
a continuous chain via connecting parts between them. These may
comprise, for example, incomplete cuts on adjacent sides of the
abrasive product. When rows of successive abrasive products in a
material strip are not die cut completely loose from each other,
they can be simply packed by rolling them up into a roll or folded
into a zigzag chain to facilitate transportation and later
handling. In the die cutting of such continuous chains, the
connecting part between the successive abrasive products preferably
form a shared tear line weakened by the die cutting in such a way
that the abrasive products can be easily detached from each other
in further handling.
[0048] In order to manufacture a flexible abrasive product 2 of the
above kind, a die cutting tool is advantageously used which
comprises blades arranged to form substantially rectilinear cutting
lines 4. These blades are further arranged to form the cutting line
in such a way that when completed, the line is of the shape of a
polygon. Further dividing the blades into at least two successive
die cutting elements simplifies the die cutting process itself and
guarantees complete through cutting. In such an embodiment, the
blades arranged to provide a cutting line on adjacent sides of the
polygon element may, for example, be arranged in different die
cutting elements.
[0049] In its particular embodiment, the die cutting tool comprises
two die cutting elements arranged to provide a cutting line 4 on
the sides of the polygon in such a way that at the first die
cutting stage the shared cutting lines of the adjacent abrasive
products 2 are left uncut in the transportation direction of the
material strip. At the same time, also at least one of the shared
cutting lines in the cross-direction of the material strip 1 is
left uncut. Thus, the continuous material strip and abrasive
products provided by it can maintain their tension and shape in the
forward feeding to the second die cutting stage, where the abrasive
product is finally detached from the material strip.
[0050] To guarantee reliable detachment of the abrasive products 2
from the material strip and the adjacent abrasive products, the die
cutting tool comprises blades arranged to provide cutting lines 4
that partly overlap each other. Furthermore, the die cutting tool
also preferably comprises blades for die cutting of dust extract
openings 3 in the abrasive product, i.e. what are called tube
punchers, or the like die cutting means.
[0051] The die cutting tool may have different structures and thus
comprise for instance a cutting plate and a blade holder with
related blades or a cutting tool with a piston-like die-cutting
part, which cuts against the edge of a corresponding groove when
the piston-like part is pressed into the groove.
[0052] The above description and the related figures are only
intended to illustrate the present abrasive product as well as the
method and apparatus for manufacturing thereof. Therefore, the
solutions are not restricted merely to the embodiments described
above or in the attached claims, but a plurality of variations or
alternative embodiments are possible within the idea described in
the attached claims.
* * * * *