Note: Descriptions are shown in the official language in which they were submitted.
CA 02293220 1999-12-23
Material processing belts in particular grinding. sanding and/or nolishin~
belts and a method of manufacturing such belts
The present invention relates to material processing belts, in particular
grinding, sanding and/or
polishing belts, and to a method of manufacturing material processing belts.
A material processing belt of the type referred to here, in particular a
grinding, sanding and/or
polishing belt, possesses a working surface, a first and second end, and also
joining means provided
at the ends for the purpose of forming an endless belt.
Such grinding, sanding or polishing belts are used in the form of ring-shaped
endless belts for
grinding, sanding or polishing circular pipes or tubes, circular wooden
workpieces, or similar items.
For this purpose, the abrasive belt is, on the one hand, slipped laterally
onto the workpiece to be
processed and, on the other hand, it is placed around the belt drive roller of
an abrasive belt machine.
However, in order to be able to process enclosed workpieces, where it is not
possible to slide the
abrasive belt laterally onto the workpiece, the abrasive belt must be
separated and placed around the
item to be worked and it must then be rejoined to form a ring once more.
One way of rejoining the separated abrasive belt is to arrange the belt to
form a ring and then to bond
a special fabric tape over the entire length of the belt. Although this method
is very effective and
reliable, it is also on the other hand very time-consuming. In addition, it
requires considerable
amounts of adhesive tape.
Another way of rejoining separated grinding, sanding and polishing belts to
form an endless ring-
shaped belt is known from WO 97/20 663. In the case of the grinding, sanding
and polishing belts
described there, the ends are joined together not by bonding the entire belt
but by bonding only a
relatively short section near the ends of the belt.
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CA 02293220 2003-12-18
Good results have already been achieved with this solution. However, adhesive
tape is still required
to reclose the belt, and opening up such an adhesive joint is still relatively
time-consuming because
a tool, such as a pair of scissors, is needed.
Furthermore, the adhesive joints cannot be repeatedly resealed. Consequently,
this frequently
means that a new piece of adhesive tape is required. This results in undesired
consumption of
material and means that each material processing belt can only be opened and
closed a limited
number of times.
In addition, in the case of the prior art material processing belts, when the
working surface is
exposed to heavy wear while in operation, the material processing belt
frequently has to be
replaced.
As a result of the disadvantages of the state-of the-art material processing
belts, one of the tasks of
the present invention is to propose a material processing belt, in particular
a grinding, sanding or
polishing belt, that is easily separated, that can easily be rejoined to form
a ring-shaped endless belt,
and that also has a long service life. In addition, a method for manufacturing
such material
processing belts is proposed.
This task is solved by means of a material processing belt having a working
surface (3), a first and
a second end (5, 7), as well as joining means at the ends of the belt in order
to form an endless belt,
characterized in that the joining means take the form of a separable positive-
locking connection (9)
having at least one opening (11) at the first end (5) as well as at least one
mating element (13) at the
second end (7), also by a material processing belt having an endless ring
shape, and possessing a
first working surface (15) and a second working surface (17) on the side
opposite the first working
surface (15), whereby in a first state of the material processing belt (1) the
first working surface
(15) is positioned on the outside, and whereby in a second state of the
material processing belt (1)
the second working surface (17) is positioned on the outside, and whereby the
material processing
belt ( 1 ) may be reversibly changed from the first state to the second stat,
and by a method for
manufacturing material processing belts characterized in that a first and
second blank of a material
processing belt (1) are manufactured from adjacent parts of the said belting
material, and also
characterized in that in the first blank at least one opening (11) and in the
second blank at least one
mating element (13) are produced in a common processing step using one or more
punching tools.
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CA 02293220 2003-12-18
Advantageous further developments and embodiments of the material processing
belts according to
the invention or of the methods for the manufacture thereof are claimed in the
sub-claims.
According to the invention, in the case of a material processing belt of the
type described above, the
joining means take the form of a separable positive-locking connection having
at least one opening
at the first end and at least one mating element at the second end of the
belt.
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CA 02293220 1999-12-23
One core idea of the invention is that the two ends of a material processing
belt are joined by means
of a positive-locking connection and that the ends of the material processing
belt are appropriately
formed. Tests have surprisingly revealed that material-processing belts whose
ends are joined in the
manner according to the invention by a positive-locking connection possess
extremely good running
properties. Compared to an adhesive joint, the transition at the joint is
smoother, so that the presence
of the transition point is scarcely noticeable when the belt is in operation.
Furthermore, one important advantage of the solution according to the
invention is that the positive-
locking connection can be opened and closed as often as required. In addition,
no further materials
and/or tools are required to produce and undo the connection. This also means,
in particular, that no
waste material is produced. In addition, the positive-locking connection can
be opened and closed
very quickly, which is also of considerable practical benefit.
Finally, it is advantageous that the material processing belts do not have to
be pre-closed, but can
be shipped and stored in the open state, thereby saving space.
Furthermore, according to the present invention, a material processing belt,
and in particular an
endless, ring-shaped grinding, sanding and polishing belt, is provided with a
first working surface
and a second working surface on the opposite side to the first working
surface; in a first state of the
material processing belt the first working surface is situated on the outside,
and in a second state of
the material processing belt the second surface is situated on the outside,
and the material processing
belt can be reversibly changed over from the first state to the second state.
The advantages of this material processing belt are in particular evident when
the belt is fitted with
a separable positive-locking connection, because it is then possible to open
and rejoin the material
processing belt very quickly and easily so that the respective other working
surface is now located
on the outside.
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CA 02293220 2003-12-18
Furthermore, one major advantage of such a material processing belt is that
practically the entire
surface can be used as a working surface. As a result, the service life of
such a material processing
belt is increased and costs of materials can be saved.
Finally, in the case of a method for manufacturing material processing belts
from belting material
supplied by the metre, the invention provides for a first blank and a second
blank of a material
processing belt to be manufactured from adjacent sections of the said belting
material, and it also
provides for at least one opening to be produced in the first blank and at
least one mating element to
be produced in the second blank, using one or more punch tools in one common
processing step.
The core idea in this case is that two blanks for material processing belts
situated adjacent to each
other in the belting material supplied by the metre can be processed in one
common processing
step, thereby speeding up the manufacturing process.
In particular, with this method, it is possible to do away with time-consuming
adjusting and
tensioning processes as well as adjustments of the workpieces, which also
require a lot of
apparatus. In addition, the method according to the invention creates fewer
rejects and only a very
small amount of waste material.
The material processing belt having a working surface (3), a first and a
second end (5, 7), as well as
joining means at the ends of the belt in order to form an endless belt,
characterized in that the
joining means take the form of a separable positive-locking connection (9)
having at least one
opening (11) at the first end (5) as well as at least one mating element (13)
at the second end (7) can
be advantageously further developed by providing at least two openings at the
first end and a
corresponding number of mating elements at the second end. As a result, the
tensile forces acting
on the joint when the belt is operating are distributed over several positive-
locking connections.
This can be advantageous, in particular in the case of relatively wide
grinding, sanding and
polishing belts.
In a preferred embodiment of a material processing belt, at least one opening
is in the form of a
punched hole and at least one mating element has a head-shaped configuration.
This permits
particularly easy and rapid separation and rejoining and offers high load-
bearing capacity while in
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CA 02293220 1999-12-23
operation. By a head-shaped formation is meant here in particular a one-piece
structure consisting
of a wide section, the "head", and a neck-like narrow section at the end of
the belt.
Such a material processing belt can be advantageously further developed by
cutting the hole so that
it is elongate in configuration and so that its length corresponds
approximately to the width of the
material processing belt. The second end of the belt, carrying the mating
element, can then be
inserted in a simple manner into the hole on the first end of the belt in
order to join the two ends of
the belt together.
In this regard, it is especially preferred to design the material processing
belt in such a way that the
longitudinal axis of the hole runs parallel to the longitudinal sides of the
material processing belt and
so that the hole possesses a first and a second section, the dimension of the
first section, in the
transverse direction of the material processing belt, being larger than the
corresponding dimension
of the second section. It is further advantageous in this connection if the
hole is positioned in such
a way that the first section faces towards the first end and the second
section faces away from the
first end. Finally, it is advantageous for the mating element to be formed by
cutting indentations at
opposite points on both longitudinal sides at the second end of the belt.
In the case of a hole and a mating element designed in the described manner,
the positive-locking
connection is closed as follows: First, the second end is introduced into the
elongated hole until the
indentations at the second end lie approximately in the plane of the first
end. Then, the second end
is displaced in the hole until the neck section formed by the indentations is
situated in the first
section of the hole, whose dimension in the transverse direction of the
material processing belt is
preferably large enough to permit the positive-locking connection to be formed
by twisting the
second end in the hole.
If the carrier material of the material processing belt exhibits mechanical
properties that do not
permit a positive-locking connection of adequate stability to be formed by a
hole and mating
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CA 02293220 2003-12-18
element, it may be advantageous to reinforce the area around at least one hole
and/or around at least
one mating element.
This can advantageously be done by applying a hard-setting agent to the area
surrounding at least
one hole and/or at least one mating element to achieve the reinforcing effect.
In order to make it still easier to separate and close the positive-locking
connection, it may also be
advantageous for the edges and/or corners of the material processing belt to
be rounded. This
makes it easier, for example, to introduce the second end into the
longitudinal hole and then to twist
said second end in the hole.
The presence of two working surfaces on the material processing belt having an
endless ring shape,
and possessing a first working surface (15) and a second working surface (17)
on the side opposite
the first working surface ( 1 S), whereby in a first state of the material
processing belt ( 1 ) the first
working surface (15) is positioned on the outside, and whereby in a second
state of the material
processing belt (1) the second working surface (17) is positioned on the
outside, and whereby the
material processing belt (1) may be reversibly changed from the first state to
the second state;
permits, for example, the first working surface to have the form of a grinding
or sanding surface
and the second working surface to have the form of a polishing surface. Such a
material processing
belt is an extremely practical tool, especially when it is provided with an
easily separable
positive-locking connection, because many work processes require that first
grinding or sanding
and then polishing is carried out. Thus, the material processing belt
described here is at one and the
same time both a grinding/sanding and a polishing belt.
For other applications, it may however also be preferred that the first and
second working surfaces
are designed as grinding/sanding or as polishing surfaces. Such material
processing belts may, for
example, be preferred when very large surfaces need to be ground, sanded or
polished, i.e. when it
can be expected that at least one working surface will be worn out during the
processing. When this
happens, it is not necessary to obtain and install a second material
processing belt, but instead, once
the first working surface of a material processing belt has been worn away,
the belt can be reversed
and then the second working surface can be used.
CA 02293220 1999-12-23
Similarly, for certain applications, it may also be useful to have material
processing belts whose first
and second working surfaces are designed as grinding or sanding surfaces
having abrasive grit of
various sizes or as polishing surfaces having different degrees of fineness.
In a preferred further development of the method according to the invention
according to claim 15,
the first blank and the second blank are separated from each other, after
undergoing the common
processing step. If it is intended to round off the edges of punched holes and
indentations in the
material, for example, in a further processing step following the common
processing step, it may be
advantageous if both blanks are not yet separated from each other.
If, however, it is not planned to carry out any further processing steps when
manufacturing the
material processing belts, it may be advantageous if the first blank and the
second blank are
separated from each other during the common processing step.
If the belting supplied by the metre is made of a relatively tough or hard
material, it may be desirable
to reduce the punching force required. This can be done by carrying out the
punching operations at
staggered intervals in order to distribute the necessary punching force.
In preferred embodiments of the methods according to the invention, the
belting supplied by the
metre consists of one of the following materials: belting made of felt or non-
woven material, textile
belting with a layer of abrasive grit, a composite material having a layer of
glass filaments and a
layer of non-woven nylon material permeated with abrasive grit, or a composite
material having two
abrasive belts which are bonded together, back-to-back.
If the hole or the mating element does not possess sufficient mechanical
strength, it may be preferred
to employ a further development of the method, wherein an area surrounding at
least one hole and/or
surrounding at least one mating element is reinforced by applying a hard-
setting material. This can
be done, for example, by immersing the ends of the belt blanks in an
appropriate agent, such as bone
glue, phenolic resin or similar.
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CA 02293220 1999-12-23
In the following, the invention is explained on the basis of the Figures,
namely:
Fig. 1 which shows three examples of holes punched at the first end of a
material processing belt
according to the invention;
Fig. 2 which shows three examples of the mating elements at the second end of
a material
processing belt according to the invention;
Fig. 3 which shows an example of a material processing belt according to the
invention, said belt
possessing two openings at the first end and correspondingly two mating
elements at the
second end;
Fig. 4 which shows a cross section through a material processing belt
according to the invention,
said belt having two working surfaces.
In Fig. 1, drawings a, b and c depict three embodiments of openings 11 at the
first end 5 of a material
processing belt 1 according to the invention. In each case, the openings 11
are made by punching
holes of different configuration. In each case they are elongate in shape,
with the longitudinal axis
25 of the hole running parallel to the longitudinal sides 27 of the material
processing belt 1, and the
length 21 of the hole corresponding to the width 23 of the material processing
belt 1.
In addition, the holes in each case possess a first section 29 and second
section 31. The dimension
37 of the first section 29 in the transverse direction of the material
processing belt 1 is larger than
the dimension 35 of the second section 31. The first section 29, which has the
larger dimension 37,
faces towards the first end 5, and correspondingly the second section 31 faces
away from the end 5.
In the example illustrated in 1 a, the first section has the form of a round
hole and the second section
has the form of an elongated hole. In the embodiment illustrated in lb, the
hole is T-shaped. Finally,
Fig. lc shows an example of a hole that is substantially trapezoidal in shape.
The dimension of the
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- CA 02293220 1999-12-23
hole in the transverse direction of the material processing belt 1 decreases
with increasing distance
from the first end 5.
In Fig. 2, the drawings a, b and c depict three examples of possible head-
shaped mating elements
13 for the openings 11 shown in Fig. 1. Equivalent parts are denoted by the
same reference numbers
in Figures 1 and 2. Each of the mating elements shown in Fig. 2 can be
connected to each of the
openings 11 shown in Fig. 1. The mating elements 13 provided at the second end
7 of a material
processing belt are in each case formed by cutting indentations 39 at opposite
points on the
longitudinal sides 27 of the material processing belt 1. These indentations 39
create a neck-like
narrowing of the belt. The variants depicted differ as regards the shape of
the indentations 39, which
in 2a are rounded, in 2b square and in 2c trapezoidal in shape.
Given the different shapes of the opening 11 and the mating element 13, and by
combining the
different variants, it is possible to create positive-locking connections
having various degrees of
strength.
Fig. 3 shows an example of a material processing belt 1 in which a positive-
locking connection is
achieved by means of two openings 11 at the first end 5 and correspondingly
two head-shaped
mating elements 13 at the second end 7.
In the case of relatively wide material processing belts 1 it is possible, in
this way, to achieve more
uniform distribution of the forces acting on the positive-locking connection
when the belt is in
operation.
Fig. 4 shows an example of a material processing belt 1 having a first and a
second working surface
15 or 17. The material processing belt 1 consists of two textile belts 51
coated with a first and second
layer 53 and 55 respectively of abrasive grit. The first working surface 15 is
formed by the first layer
of abrasive grit 53 and the second working surface 17 is formed by the second
layer of abrasive grit
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CA 02293220 1999-12-23
55. The textile belts 51 are joined to each other at the sides opposite the
layers of abrasive grit 53
and 55 respectively by means of a layer of adhesive 49.
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