EP2990171B1

EP2990171B1 - Method and device for localised thermal-melting

Info

Publication number: EP2990171B1
Application number: EP15179806.3A
Authority: EP
Inventors: Giuseppe Pritelli
Original assignee: GP Consulting Di Giuseppe Pritelli & C Sas
Current assignee: GP Consulting Di Giuseppe Pritelli & C Sas
Priority date: 2014-08-21
Filing date: 2015-08-05
Publication date: 2018-12-05
Anticipated expiration: 2035-08-05
Also published as: EP2990171A1

Description

DETAILED DESCRIPTION

State of the art

The invention refers to a method for localised thermal-melting for thermo-activating the adhesive face of an edging strip for continuously joining an edging strip on the edge of a panel and to a device for implementing such method according to the preambles of claim 1 and 3 respectively, known from WO 2009/026977 .
The edging technique, i.e. the perimeter application - on the thicknesses of wooden or, more often, surrogate wooden panels - of strips made of coating material for the quality enhancement and/or only covering/decorative purposes, made of various materials, is known in the furnishing industry.
In the usual embodiments, these strips of coating material are made of synthetic material webs, continuously applied by automatic machines, the so-called edging machines, which unwind the strip from reels, cut it into suitable segments to suit the panel perimeter, apply bonding material thereon on a face or activate the bonding material already pre-existent and make it adhere on the perimeter with respect to the panel, precisely at the thickness of the relative edge, unless in case of subsequent filing.
In the most modern implementation, these strips of edging material are made of polymeric strip material, usually polypropylene, made of one component but obtained in two co-extruded layers differentiated by the melting point: the layer intended to be exposed to view in the finished product has a higher melting point, while the inner layer has a lower melting point, so as to be more suitable to be thermo welded, in solidification, to the edge of the panels without need for further resins and/or bonding agents.
The thermo activation of the meltable face of polymeric edging webs thus made requires considerable heat, which, according to the prior art, is attained through laser beams, spread on the inner face of the strip through vibrating mirrors, or through optical cylinders.
GB 1 477 196 discloses a process and an apparatus for metallising sheet-like substrates.

Description of the specific technical drawback

These known thermo activation systems of polymeric edging webs thus made reveal considerable drawbacks and limits in terms of high costs of purchase and management of the laser beam generators, as well as in terms of risks to the physical safety of the operators, also considering the well known risks that may arise from high power laser beams.

Objects of the invention

In such context, the main object of the present invention is that of providing an innovative system for the thermo-activation of the bonding face of the edging strips in the furnishing industry, especially the meltable face of the one-component polymeric strips coextruded in two layers with differentiated melting point, so as to be efficient and feasible in the functions as well as easily applicable to the existent production lines, without revealing drawbacks, contraindications or inconveniences in terms of costs and safety.
Another object of the present invention is to attain the preceding object through a polyvalent system in terms of the dimension of the strip, adjustable according to the dispensable heat, low in terms of consumption and energy dispersion, modular in terms of application alternatives, simple in terms of maintenance and interchangeability, which can also be adapted to pre-existing systems and not explicitly conceived or designed to receive it.
A further object of the present invention is to attain the preceding objects through a simple and efficient system, that is safe in the operation and relatively low costs considering the results practically obtained therewith.

Summary of the solution concept

These and other objects are attained through a method and device as set forth in claim 1 and 3 respectively.

Description of the attached drawings

Further characteristics and advantages of the method and device according to the invention shall be more apparent from the following detailed description of a preferred but non-exclusive embodiment thereof, represented solely by way of non-limiting example in the attached drawings, wherein:

Figures 1 and 2 respectively show a perspective and a plan view of an embodiment of a device according to the present invention;
Figure 3 shows a perspective view of an alternative embodiment of a device according to the present invention;
Figures 4 and 5 show two perspective views from substantially opposite angles of an embodiment of a device according to the present invention as applied to an edging group of panels on straight edges as schematically illustrated;
Figures 6 and 7 respectively show a perspective view and a lateral view of an embodiment of a device according to the present invention as applied to an edging group of panels on shaped edges as schematically illustrated.

Static description of the invention

With reference to such figures, and in particular to figure 1, an embodiment of the device 1 for localised thermo-melting according to the present invention, comprises a body for example metallic 2, substantially parallelepiped-shaped in the illustrated embodiment, within which there is obtained a cavity 3, describing an elliptical-shaped semi-cylinder with mirror surface, hereinafter also referred to as elliptical mirror 3, cut parallel to the generatrices for planar cutting on a face of the parallelepiped-shaped body 2, substantially adjacent in the axis of one of its two geometric focuses F2 (also see figure 2), thus obtaining said focus F2 slightly external with respect to the elliptical mirror 3.
The surface of the elliptical mirror 3 is preferably obtained with polished coating, in turn covered by a material capable of guaranteeing maximum reflection with respect to thermal radiation, for example gold.
In the elliptical mirror 3, substantially at the axis at the other of its two geometric focuses F1 (also see figure 2), there is arranged a plug 4 for generating suitably supplied infrared rays, whose fixed emission active segment preferably extends over the entire height of the elliptical mirror 3; it is fixed to a basement bracket 5, to which there is also fixed the parallelepiped-shaped body 2, for example by means of two pins 6 preferably ceramic pins.
In the alternative illustrated in figure 3 there is shown a variable emission plug 4, whose active segment is defined by an elastic gripper element 4A carried by a mobile electrode 4B
The parallelepiped-shaped body 2 preferably has a plurality of external cooling fins 7 and thus it may be exposed to a forced air flow which, through channels (not illustrated), may also be driven to carry, in slight positive pressurisation, the internal compartment of the parallelepiped-shaped body 2, i.e. elliptical mirror 3; the cooling may also be of the liquid type, thus hereinafter for the alternative embodiments.
At the axis of the geometric focus F2 of the elliptical mirror 3, externally with respect thereto, there is arranged the sliding passage 8 of an edging strip 9, of the one-component polymeric type obtained in two co-extruded layers differentiated by the melting point, called pitch preferably being defined on the other side by two retroflex edges 10.
The edging strip 9 is advanced and driven, like in the prior art, by batteries of driven and idle rollers 11, which, downstream of the device for localised thermo-melting 1 according to the present invention, lead it to converge and thus press it on the edges 12 of wood or wood surrogate panels 13 carried to transit in succession by a conveyor 14, for continuous joining therewith according to the prior art, for the functions to be specified hereinafter.

Dynamic description of the embodiment

Thus, having completed the static description of a preferred embodiment of the device for localised thermo-melting according to the present invention, following is a dynamic description of the same:
The edging strip 9 is of the one-component polymeric type, usually polypropylene, obtained in two co-extruded layers differentiated by melting point: the layer intended to be exposed to view in the finished product has a higher melting point, while the inner layer has a lower melting point, so as to be more suitable to be thermo welded, in solidification, to the edge 12 of the panels 13 without need for further resins and/or bonding agents.
Like in the edging machines of the prior art, the edging strip 9 should be unwound from a supply reel, not illustrated, and advanced on a path by rollers 11 of the known type.
According to the present invention, when the edging strip 9 reaches before the device for localised thermo-melting 1, its pitch occurs substantially at the second focus F2 of the elliptical mirror 3, externally but immediately adjacent to the elliptical mirror 3.
In this position, the heat radiation emitted by the plug 4, or any other source of 360° infrared radiation suitably shaped for the purpose arranged on the axis of the first focus F1, impacts the meltable face of the strip 9 with direct radiation on an angle α determined by the interspace between the edges of the planar cutting on the open face of the parallelepiped-shaped body 2 (particularly see figures 1 and 2).
In addition, on the angle with vertices on the axis of the plug 4 with respect to angle α, all heat radiations are reflected by the elliptical mirror 3 on the axis of its second focus F2, i.e. on the meltable surface of the strip 9 passing therethrough, affecting the latter obtaining an angle β (particularly see figures 1 and 2) concentrated on the focal axis F2.
This combined direct and indirect flow of infrared rays transfers from the first focus F1, i.e. from the source of heat 4, to the second focus F2, i.e. to the surface of the strip 9, about 90% of the heat energy generated by said source 4, which, if of suitable power, easily obtains the thermo-melting of the meltable face of the edging strip 2, i.e. the activation of the bonding face, without any contacts or adverse effects whatsoever in terms of safety and energy costs which are absolutely acceptable, even in terms of reducing dispersion.
The edging strip 2 with internal surface thus may thus continue its movement, according to the prior art, to be driven adjacent to the edges 12 of the panels 13 and pressed thereon by the special rollers 11 to adhere - by interstitial penetration of the polymeric resin after the cooling and solidification of the molten face.
The heat absorbed by the metal body 2, where the elliptical mirror 3 is provided, may be dissipated through fins 7, possibly with the help with a source of airflow of the known type.
This flow may be advantageously channelled into the elliptical mirror 3 to maintain the relative environment with slight positive pressure, so as to evacuate the stagnation of possible fumes.
Also advantageously, the localised thermo-melting device may be provided with a hinging element and which can be diverged through operative positioning, possibly with the part of the rollers adjacent thereto, or removable from the seat thereof for easy cleaning interventions against sedimentation of fumes and replacement of the entire device and its components.

Alternative embodiments

It is obvious that in further alternative embodiments still falling within the solution concept underlying the embodiment illustrated above and claimed below, the device for localised thermo-melting according to the present invention may be alternatively implemented through equivalent technical and mechanical elements, by means of devices possibly complemented by further integrative solutions, still falling within the solution concept illustrated above and claimed below.
In particular:

the heat generator may alternatively be made of any type of known device, or unknown to the state of the art, suitable for the purpose;
the body in which the elliptical mirror is obtained may alternatively be made of other materials other than metal, for example ceramic material, as well as alternatively shaped in any manner suitable for the purpose and it may alternatively be cooled with a liquid through suitable interspaces, ducts and heat exchangers;
the elliptical mirror may be variously shaped with variation of the interfocal distance;
the axial segment of the fulcrums, and also the height of the elliptical mirror, may be of any size capable of housing the height of the edging strips to be applied; in order to save energy, the axial sources of heat radiation may be designed to be activated even only as regards their portions, as illustrated in the alternative embodiment of figure 3, when applying edging strips with low height.

Advantages of the invention

As observable from the detailed description of a preferred embodiment outlined above and from the variations outlined above, the method and device for localised thermo-melting according to the present invention offers advantages corresponding to the attainment of these and other preset objects: as a matter of fact it integrates a functional, modular, polyvalent and safe method and device (with reference to the safety standards of the machines of the industry) suitable for the thermo-activation of the bonding surfaces of the edging strips especially in the furniture industry, which can also be adapted to pre-existing and operating systems even not explicitly designed to receive them.

KEY TO THE REFERENCE NUMBERS

1): device for localised thermo-melting in its entirety
2): parallelepiped-shaped metal body defining the elliptical mirror
3): elliptical mirror
4): plug
4A): elastic gripper element in figure 3
4B): a mobile electrode in figure 3
5): basement bracket
6): ceramic pins
7): cooling fins
8): sliding passage of the edging strip
9): edging strip
10): retroflex edges
11): driving, return and pressure rollers
12): sides of the panels
13): panels
14): panel conveyor
F1): first focus of the elliptical mirror
F2): second focus of the elliptical mirror
α): direct radiation angle
β): indirect radiation incidence angle

Claims

Method for localised thermal-melting for thermo-activating the adhesive face of an edging strip (9) for continuously joining the edging strip (9) on the edge (12) of a panel (13) made of wood or wood surrogate in an automatic edging strip processing device (1) for the industrial production of furniture, said strip (9) being of the one-component copolymer type comprising two co-extruded layers differentiated by the melting point with a layer having a higher melting point with exposed surface in the finished product and layer having a lower melting point with inner meltable face suitable to be thermal-molten for solidification adhesion to the edge (12) of the panel (13) without the help of further resins and/or bonding agents, characterized in that a heat radiation generator means (4) is positioned at one of the two focus axes (F1) of an elliptical-shaped semi-cylindrical mirror (3) whereas the other focus axis (F2) is localized outside of said elliptical mirror (3) and in a sliding passage (8) of the edging strip (9) passing through said edging device (1) in which it is subsequently pressed to the edge (12) of the panel (13).
Method according to claim 1, wherein said heat radiation generator means (4) is producing infrared rays.
Automatic continuous edging strip processing device (1) for localised thermal-melting, for thermo-activating the adhesive face of edging strips (9) for the industrial production of furniture, for implementing the method of claim 1 or 2, characterized in that the edging strip processing device (1) comprises heat radiation generator means (4) positioned substantially at one of two focuses (F1) of an elliptical-shaped semi-cylindrical mirror (3) and a sliding passage (8) located substantially at the other focus (F2), the sliding passage (8) suitable for edging strips (9) to pass guided thereon and constrained so as to supply the edging strip processing device (1) with continuous adhesive confluence to the edge (12) of panels (13) made of wood or wood surrogate.
Device according to claim 3, characterized in that it comprises
- a body (2) defining a cavity forming said elliptical-shaped semi-cylindrical element (3) with mirror surface cut parallel to the planar cutting generatrices of the constituting structure of said body (2) substantially internally adjacent to the axis of one of its two geometric focuses (F2) thus leading to said second focus (F2),

- segment-shaped means (4) for generating heat radiation housed in said elliptical mirror element (3) substantially at the first axis (F1) of the two geometric focuses of said elliptical mirror element (3) whose active segment extends over part or the entire height of the elliptical mirror element (3), wherein

- said sliding passage (8) for the edging strip (9) that is located substantially at the second focus axis (F2) is outside of said elliptical mirror element (3) and orthogonally with respect to it,

- rollers (11) are positioned downstream of the body (2) of the processing device (1) adapted to automatically lead said strip (9) to converge and to press it on the edge (12) of the panel (13).
Device according to claim 4, wherein said sliding passage (8) for said edging strip (9) is defined by two opposed retroflex edges (10).
Device according to claim 4 or 5, comprising a conveyor (14) adapted to carry and to transit in succession the panels (13) in said device (1).
Device according to claim 4, 5 or 6, wherein said heat generating means (4) is constituted by a glow plug (4) for generating infrared rays whose active segment extends over the entire height of the elliptical mirror (3).
Device according to anyone of claims 4 to 7, wherein said body (2) is a parallelepiped-shaped metal body provided with external cooling fins (7) or with interfaces for the circulation of a cooling fluid.
Device according to anyone of claims 4 to 7, wherein said body (2) is a parallelepiped-shaped metal body with channelling means for conveying airflow adapted to bring the compartment forming said elliptical mirror element (3) to positive pressure levels.