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The present invention relates to machines for automation
of production of articles obtained by working flat
material, and in particular, the present invention
relates to a machine for automatic cutting off the above
mentioned articles, mainly in leather or similar
materials, used principally in the production of footwear
and other articles of leather.
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As it is known, articles made of leather or similar
materials, e.g. footwear, are usually obtained from a
plurality of components made of leather or similar
materials, suitably shaped and worked in relation to the
article model and joined together by stitching.
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The components are cut out from big leather pieces and
then possibly decorated by series of holes or slits.
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During production of one series of products, in
particular footwear, a great number of parts of various
shapes and sizes are produced, since many models of upper
are produced and each upper is composed of several parts.
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Furthermore, every shoe upper model is usually produced
in different sizes and colors and, lastly, the parts of a
right upper are symmetrical with the parts of a left one.
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Cutting these parts must be very accurate, so as to
guarantee high and constant production quality.
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Another problem involved while cutting the pieces of the
shoe uppers, relates to optimum exploitation of the
material. As it has been already said, the parts are cut
out from big pieces of leather, which usually have
irregular shape and are always different. Therefore, it
is necessary to plan and pre-set the number and best
arrangement of the parts to be cut out every time, so as
to occupy a surface of the leather piece as big as
possible, without making component cutting areas overlap
one another and reducing off-cuts.
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This concerns substantially also most of the articles
made of leather or similar materials.
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Thus, it is obvious that the cutting operations are
rather complicated and require a lot of resources.
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These operations are carried out automatically by complex
cutting machines helped by a processor, so as to improve
the productivity and reduce use of specialized manpower,
as well as operation time.
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In particular, the cutting machines have heretofore been
provided, as including a large working plane, over which
an arm slides longitudinally and supports a tool carrying
head, which moves along the arm.
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The tools are moved along Cartesian axes on the entire
surface of the working plane by a combined movement of
the arm and the head.
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The tools include bits of different thickness for making
holes, particular blades for straight and curved cutting,
and others.
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The movable arm usually slides along one or more guides
which extend parallel to the working plane.
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The arm and the tools carrying head are driven by a
computerised system of the machine according to known
techniques of digital definition of the paths.
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The driving commands are issued in response to data which
define the profiles of various parts to be cut out, and
which are stored in the above mentioned system.
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The arrangement of the profiles can be set on a monitor
by an operator, or can be automatically optimised by
suitable calculation algorithms after the leather has
been arranged on the working plane and after its outline
and position have been scanned by known techniques.
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The main limit for efficiency and productivity of the
above mentioned machines derives from the speed of
leather cutting and drilling operations.
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In fact, all other operations, like complicated
calculation of the best arrangement of the profiles and
coding the driving commands for the arm and tool carrying
head are carried out automatically by the machine
processor.
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Due to the current performance continuous and quick
improvement of the electronic data processors, which can
be compared only with their prices reduction, the
processor unit carries out the above mentioned operations
in much shorter time than the corresponding mechanical
means.
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From the other side, the linear velocity and acceleration
of the arm and tool carrying head cannot be increased
indefinitely because of inertia, control power and
material resistance.
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The main object of the present invention is that of
providing a machine for cutting leather and the like,
which makes optimum use of the machine controlling
processor system, so as to obtain much better performance
than the cutting machines used so far, and therefore, for
improving the machine productivity and efficiency.
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Another object of the present invention is to fulfil the
above mentioned object by only small increase of the
machine production cost.
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A further object of the present invention is to obtain
the above mentioned objects without affecting machine
reliability, simplicity of use and maintenance operation.
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The above mentioned objects are fully obtained in
accordance with the invention as claimed.
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The characteristic features of the present invention will
become more fully apparent from the following detailed
description, taken in conjunction with the accompanying
drawings, in which:
- Figure 1 shows a schematic view of a machine obtained
according to the present invention, in a usual working
position;
- Figure 2 shows a schematic view, in crosswise section,
of a possible sliding mechanism for arms of the machine
of Figure 1.
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With reference to Figures 1 and 2 and to a preferred
embodiment of the present invention, reference numeral 1
indicates a substantially horizontal working plane of a
machine 100 used for cutting components 2 forming parts
of articles made of leather or similar materials, such as
shoe uppers, bags, leather garment and others.
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One or more pieces of leather 3, indicated partially with
broken line, are put on the working plane 1 to be cut,
pierced and so on, in order to obtain the above mentioned
components.
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First cutting means 30 and second cutting means 50,
situated over the working plane 1, are aimed at cutting,
piercing and performing other operations on the pieces of
leather 3, in a substantially independent way.
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The machine 100 includes also a substantially
parallelepiped base 101, whose top portion forms the
above mentioned working plane 1, that is located at such
level as to allow an operator to have an easy access to
it.
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A longitudinal horizontal member 4, fastened along one of
the longer sides of the base 101, supports slidingly in
known way the first cutting means 30 and the second
cutting means 50, which are substantially coplanar.
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The machine 100 includes also a processor unit 7, which
controls the machine working cycle. The processor units
also have stored therein the digitised shape data of all
components 2 to obtain, and also a known program for
optimising the arrangement of the profiles of the
component 2 on the piece of leather 3 and for
automatically guiding the first cutting means 30 and the
second cutting means 50.
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The processor unit 7 is suitably equipped with a monitor
8, which allows the operator to follow and possibly
modify all the operations performed by the machine 100,
and with a keyboard or other means for data input, not
shown for simplicity's sake.
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The first cutting means 30 include a first driving arm
34, horizontal and transversal to the working plane 1,
for driving a first tool carrying head 36.
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The first tool carrying head 36 slides along the first
driving arm 34, over the entire surface of the working
plane 1, to cut and pierce the piece of leather 3
according to predetermined shapes and paths.
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The first driving arm 34 (see also Figure 2) includes a
substantially straight horizontal portion 34a, and a
connecting portion 34b, made in the above mentioned
horizontal portion 34a at the end of this latter closer
to the longitudinal member 4.
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The connecting portion 34b engages slidingly, by
substantially known sliding means 35, a guiding track 5,
situated inside the longitudinal member 4.
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The first driving arm 34 and the first head 36 are
operated, according to known techniques, by suitable
motor means, not shown, which are controlled, as has been
already said, by the processor unit 7.
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The second cutting means 50 include a second driving arm
54, similar to the above described first driving arm 34,
and a second tool carrying head 56, similar to the first
tool carrying head 36.
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The connecting portion 54b of the second driving arm 54
engages slidingly, by means of related sliding means 55,
the same guiding track 5, while the horizontal portion
54a of the second driving arm 54 supports the above
mentioned second tool carrying head 56.
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Also the second driving arm 54 and the second tool
carrying head 56 are operated, according to known
techniques, by suitable motor means, not shown, which are
controlled by the processor unit 7.
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Each of the above mentioned operating means of the first
driving arm 34 and the second driving arm 54 can include
e.g. a ball screw in engagement with a corresponding
powered rotating lead nut.
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Power means of this type are commonly used in traditional
leather cutting machines.
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In this case, the motor means of the first driving arm 34
and of the second driving arm 54 can advantageously use
the same ball screw, which obviously reduces the
production and maintenance costs.
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Obviously, the above described configuration is a pure
example, therefore other configurations, like the
presence of further independent cutting means controlled
by the processor unit 7, or further tool carrying heads
in each driving arm 34,54, remain within the protective
scope of the invention.
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The machine 100 works with one or more pieces of leather
3 placed on the working plane 1.
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The first driving arm 34 and the second driving arm 54,
with the respective tool carrying heads 36, 56, are
situated in different dwell areas of the working plane 1,
so as not to interfere with the operations of placing the
pieces of leather 3.
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At this point, scanning of the leather 3 shapes, choosing
of the component profiles 2 to be cut and/or pierced, and
optimising of the arrangement of the pieces of leather 3
are carried out in a known way, automatically or by an
operator.
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Then, the processor unit 7, using a suitable program
stored therein, prepared according to known programming
techniques, elaborates separate driving commands for the
first cutting means 30 as well as for the second cutting
means 50.
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Since the first cutting means 30 and the second cutting
means 50 are equipped with wholly independent power
means, the paths of the first tool carrying head 36 and
the second tool carrying head 56 are practically
independent one from the other.
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In fact, the first cutting means 30 and the second
cutting means 50 are limited only by the fact that the
first driving arm 34 and the second driving arm 54 slide
on the same guiding track 5, and consequently, they
cannot be placed one upon the other or step one over the
other.
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This limitation practically does not influence the tool
carrying heads operations, because the program of the
processor unit 7 can easily issue to each of the heads
commands for cutting and/or piercing components arranged
in different areas of the piece or pieces of leather 3.
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It is also to be noted that the presence of two driving
arms 34, 54 allows to obtain much bigger operative
independence with respect to e.g. two or more tool
carrying heads sliding on the same arm, because each of
the above mentioned tool carrying heads can move almost
completely autonomously on both cartesian axes.
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Therefore, the machine 100 speed of cutting and piercing
of the profiles 2 is practically doubled and the total
productivity of the machine 100 increases considerably,
since the presence of more cutting means 30, 50 allows to
use better the processor unit 7 capacity for preparing
simultaneously two or more different components arranged
in any way on the piece of leather.
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The performance improvement is obtained also with a small
increase of the machine 100 production costs, especially
if all provided cutting means 30, 50 use the same support
and guiding means.
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Another advantage of the proposed machine derives from
the fact that the cutting means are identical, therefore
the maintenance costs are low and the reliability of the
machine 100 increases.
