[0001] The present invention relates to a glue distribution unit, in particular, but without
limiting the scope of the invention, for machines which process wooden panels.
[0002] The wood-working machines, or machining centres, which will be indicated as examples
of use of the present invention, without limiting the scope of application of the
invention, are so-called edge banding machines. These machines apply a band of material,
usually synthetic, by gluing to the edge of the panel with profiles which may even
not be straight.
[0003] For panels with straight profiles, there are so-called "pass" machines, that is to
say, linear edge banding machines for the application of edging bands on the edges
of panels, in which the panel is fed forward relative to the edge banding device,
which is fixed: in these cases, the glue may be applied both on the edging band and,
preferably, on the panel.
[0004] In contrast, for panels with profiles which are not straight, there are machines
which generally comprise a work table on which a panel to be edge banded is placed
and band application means. In a first solution the work table and band application
means move relative to one another to apply the band to the entire edge of the panel
by gluing.
[0005] These solutions may involve the use of pre-glued edging bands which, immediately
before application to the panel, are subjected to a glue heating - reactivation step.
However, this method has a disadvantage in that the layer of ready-applied glue, having
to be reduced, is not always sufficient to "cover" the porous zones on the edge of
the panel. Basically, it may be said that these machines sometimes "lack glue".
[0006] Alternatively, there are band application units in which the band application means
consist of a unit with a vertical, motor-powered main shaft, supporting and driving
a roller which makes contact with the edge of the panel, turning freely about its
vertical axis which coincides with the main shaft. On opposite sides of the contact
roller there are glue feed means and there is at least one main band presser roller,
in turn attached to the main shaft and able, in some solutions, to turn relative to
the shaft according to the shape of the panel profile.
[0007] The means which distribute the glue, normally of the polyurethane type, on the edge
of the panel or on the band (of particular interest in the present invention) comprise
a tank for the glue, which is kept at a predetermined temperature by special heating
means, and which can be fed to a distribution unit which may consist of a spatula
element for contact with the edge of the panel.
[0008] At present, this type of glue distributor has the disadvantage of limited precision
of the means (normally a knurled steel roller) which apply glue on the edge of the
panels. This is due to the structure of the applicator means which is not very adaptable
and, above all, is difficult to adjust to production requirements, which often involve
the edge banding of panels with a variety of thicknesses. Moreover, this makes it
highly likely that the adhesive will be dispersed beyond the edge, or, as already
indicated, distribution on the edge will be limited, with negative effects on the
final quality of the panel.
[0009] The aim of the present invention is, therefore, to overcome the above-mentioned disadvantage
by providing a glue distribution unit for machines which process wooden panels which
is compact and extremely practical, precise and rapid when applying glue.
[0010] The technical task and preset aims are substantially fulfilled by a glue distribution
unit, in particular for machines which process wooden panels comprising means which
distribute glue on the edges of panels or on bands to be applied to the edges of panels.
The distribution means are located close to a working zone. There are also means which
feed glue to the glue distribution means through a pressurised pipe. The glue distribution
means comprise: a main body with a surface which makes contact with and distributes
glue on the edge or on the band. This surface has a longitudinal slot through which
the glue passes from a first chamber, inside the main body, to the outside of the
main body; means for adjusting the glue passage opening which operate on the slot
to vary the size of the slot according to the thickness of the edge of the panel or
the band.
[0011] The technical characteristics of the invention, with reference to the above aims,
are clearly described in the claims below and its advantages are apparent from the
detailed description which follows, with reference to the accompanying drawings which
illustrate a preferred embodiment of the invention provided merely by way of example
without restricting the scope of the inventive concept, and in which:
- Figure 1 is a perspective view with some parts cut away to better illustrate others,
of a glue distribution unit, in particular, but without limiting the scope of application
of the present invention, for machines which process wooden panels, made in accordance
with the present invention;
- Figure 2 is a top plan view of the glue distribution unit illustrated in Figure 1;
- Figure 3 is a cross-section in a plane indicated by the line III - III in Figure 2.
- Figure 4 is a perspective view with some parts cut away and other parts in cross-section,
of a detail of the unit illustrated in Figure 3.
[0012] With reference to the accompanying drawings, and in particular with reference to
Figure 1, the glue distribution unit as disclosed herein may be used, in particular,
but without limiting the scope of application of the present invention, for machines
which edge band wooden panels.
[0013] This glue distribution unit, labelled 1 as a whole, basically comprises means 2 which
distribute glue on the edges of panels or on bands to be applied to the edges of panels
(not illustrated here).
[0014] These distribution means 2 are located close to a working zone, not illustrated,
where the panels to be edge banded can be fixed in position, with distribution means
2 that are mobile or vice versa according to the type of machine used and/or the profile
of the panels to be edge banded.
[0015] The numeral 3 is used to denote means which feed glue to the glue distribution means
2, for example, by means of a pressurised pipe 4, illustrated by way of example with
cartridge containers 3a and 3b. As also illustrated in Figures 2 and 3, the glue distribution
means 2 comprise: a main body 5 and glue passage adjusting means 9.
[0016] More precisely, the main body has a surface 6 which makes contact with and distributes
glue on the edge or band and a longitudinal slot 7 in the surface 6 for the passage
of glue from a first chamber 8, inside the main body 5, to the outside of the main
body 5.
[0017] The glue passage adjusting means 9 operate upon the slot 7, varying the size of the
slot 7 according to the thickness of the edge of the panel or the band to be applied.
[0018] Specifically, as illustrated in Figures 3 and 4, the adjusting means 9 comprise a
secondary plate body 10 which complementarily engages the main body 5 at the slot
7 along its entire length.
[0019] The secondary body 10 is operated upon by drive means 11 which allow the secondary
body 10 to slide in both directions (see arrow F in Figures 3 and 4), adjusting the
zone through which glue passes in the slot 7.
[0020] The above-mentioned drive means 11 may comprise a pin 12 attached to the secondary
plate body 10, consisting of a cylindrical portion 10a and a plate portion 10b, and
controlled by an adjusting and actuating unit 13 which may be of the electrical or
mechanical type (illustrated with a generic block here).
[0021] The main body 5 comprises the first chamber 8 for the passage of the glue fed from
a second chamber 14 or glue pre-feed tank (see arrow F1 in Figure 3) connected by
a plurality of holes 15 made in a wall 16 which separates the two chambers 8 and 14
and at predetermined heights relative to the lower end of the main body 5. This architecture
allows a uniform and constant flow of glue according to the gap allowed by the adjusting
means 9.
[0022] Returning to the second chamber 14, this is operated upon by means 17 which stop
or feed glue from the second, pre-feed chamber 14 to the first chamber 8.
[0023] These means 17 comprise (again see Figure 3) a head 18 which engages with a compartment
19 for the passage of the glue from a radial glue feed pipe 4. The head 18 is attached
to a rod 21, controlled by control means 22 (of the known type and simplified with
a block in Figure 3), designed to allow the head 18 to move (see arrow F2) between
a closed position, in which the head 18 makes contact with the compartment 19, and
an open position, in which the head 18 is distanced from the compartment 19 (position
illustrated in Figure 3).
[0024] This special compartment opening and closing structure allows the creation of a vacuum,
when the glue supply is turned off, designed to instantly stop glue from passing through
the slot. Similarly, when the glue supply is turned on again, the compartment 19 is
opened by the head 18, creating a pressure designed to immediately allow glue to pass
through the slot 7 again. This structure is very important both for correct distribution
of the glue (normally polyurethane), and for preventing excessive quantities of glue
from remaining in contact with the air close to the slot, with the risk that it may
crystallise and so compromise subsequent glue distribution.
[0025] Obviously, the chambers 8 and 14 may be fitted with heating means, to keep the glue
in an optimum liquid state (not illustrated here).
[0026] In addition, it is important to consider that the slot 7 can distribute glue directly
on the edges or bands, but can also be used as an element for controlled glue feed
onto roller or spatula means, depending on requirements or the type of machine on
which the unit is fitted, without limiting the scope of application of the present
inventive concept.
[0027] The glue distribution unit disclosed, therefore, fulfils the preset aims with an
extremely compact structure, with rapid, precision distribution thanks to the system
for adjusting the size of the slot according to the thickness required for the processing
cycle.
[0028] The invention described can be subject to modifications and variations without thereby
departing from the scope of the inventive concept. Moreover, all the details of the
invention may be substituted by technically equivalent elements.
1. A glue distribution unit (1), in particular for machines which process wooden panels,
the unit (1) comprising at least: means (2) for distributing glue on the edges of
panels or on bands to be applied to the edges of panels, the distribution means (2)
being located close to a working zone; and means (3) for feeding glue to the glue
distribution means (2), the unit (1) being
characterised in that the glue distribution means (2) comprise:
- a main body (5) with at least one surface (6) which makes contact with and distributes
glue on the edge or on the band; this surface (6) having a longitudinal slot (7) through
which the glue passes from a first chamber (8), inside the main body (5), to the outside
of the main body (5);
- means (9) for adjusting the glue passage opening which operate on the slot (7) to
vary the size of the slot (7) according to the thickness of the edge of the panel
or the band.
2. The glue distribution unit according to claim 1,
characterised in that the adjusting means (9) comprise a secondary plate body (10) which complementarily
engages the main body (5) at the slot (7) along its entire length; drive means (11)
operating on the secondary body (10), allowing the secondary body (10) to slide in
both directions and adjust the zone through which glue passes.
3. The glue distribution unit according to claim 2, characterised in that the drive means (11) comprise a pin (12) attached to the secondary plate body (10)
and controlled by an adjusting and actuating unit (13).
4. The glue distribution unit according to claim 1, characterised in that the main body (5) comprises a first chamber (8) for passage of the glue fed from
a second, glue pre-feed chamber (14), the chambers being connected by a plurality
of holes (15) made in a wall (16) separating the two chambers (8, 14) and at predetermined
heights relative to the lower end of the main body (5), allowing uniform passage of
the glue according to the gap allowed by the adjusting means (9).
5. The glue distribution unit according to claim 4, characterised in that the second chamber (14) is operated upon by means (17) which stop or feed glue from
the second, pre-feed chamber (14) to the first chamber (8).
6. The glue distribution unit according to claim 4, characterised in that the second chamber (14) is acted upon by means (17) which stop or feed glue from
the second, pre-feed chamber (14) to the first chamber (8); the means (17) comprising
a head (18) which engages with a compartment (19) for the passage of glue from a radial
glue feed pipe (4), forming part of the glue feed means (3); the head (18) being attached
to a rod (21), controlled by control means (22) designed to allow the head (18) to
move between a closed position, in which the head (18) makes contact with the compartment
(19), and an open position, in which the head (18) is distanced from the compartment
(19).