This invention relates to a method for forming surface

engraved panels clad with a sheet of thermodeformabl

material, and an apparatus for implementing the method.

Methods are known for forming surface-engraved panels clad with a deformable material sheet.

One of these methods comprises a first stage in which surface of the panel, generally in the form of a chipboard

substrate, is engraved in order to form personalised effects

and designs on it accordance with the client's requirements. Over said surface a layer of glue is then spread, on which

sheet of PVC or other thermodeformable material is then applied.

The assembly is then subjected to the action of a press,

the punch of which has a shape complementary to that of • the

engraved panel. The press acts under hot conditions on -the

PVC sheet to thus cause it do adhere to the cavities in the

chipboard substrate.

However, this known method has certain drawbacks, and i particular:

- the need to correctly position the panel relative to th punch,

- the need for different punches corresponding to th different design to be formed,

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- a considerable time wastage due both to the need to repla

the punch every time the decorative panel motif change and to the laboriousness of this replacement operation.

this respect, in order to replace the punch it first has

be cooled, and after being replaced it then has to

raised to the working temperature in order to be able t

again use It.

To obviate these drawbacks , another method has alread

been proposed in whic the stages involving the engraving o the chipboard .substrate and the application of th

thermodeformable material remain unchanged, but in which th

panel is subjected to the action of a hot press, the fixe

plate of which is in the form of a chamber filled with

fluid and having that surface in contact with the pane

formed from a defor able elastic membrane. By virtue of th

pressure and temperature increase of the fluid contained i

the chamber, the membrane deforms by expanding, ^" to cause th

thermodeformable material to penetrate into the cavitie

previously formed in the chipboard substrate.

This known method, which enables the same punch to b

used for all types of design, has however other drawbacks

and in particular:

- if the membrane is of a thin type, it is impossible t

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attain high pressure and thus impossible to obtain

sufficient deformation in the case of cavities of a certain depth; in any event, the membrane undergoes stretching and

is therefore subject to frequent rupture,

- if the membrane is of greater thickness it adheres poorly

to the cavity walls, and consequently results in an

unfaithful reproduction of the design,

- its application is limited due to' the maximum attainable

pressure and temperature. In this respect, if the chamber fluid is water, it is obviously impossible to operate at a

temperature exceeding 100xC. If however the fluid is a

diathermic oil, not- only does the membrane disintegrate at

the high temperature but the oil reacts chemically with it.

The object of the invention is to obviate all these

drawbacks and to produce surface-engraved panels clad with

thermodeformable material, in a rapid, reliable and versatile manner.

This object is attained according to the invention by a

method for forming surface-engraved panels clad with a sheet

of thermodeformable material particularly PVC comprising a

preliminary stage of engraving the surface of a chipboard

substrate to obtain cavities therein in accordance with a

predetermined design and a subsequent stage in which an

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adhesive is spread over said surface followed by a sheet of thermodeformable material which cover said cavities,

characterised in that the panel prepared in this manner is

passed through at least one pair of rollers, of which the

roller In contact with said surface Is formed of elastically

yieldabie material which causes the sheet of thermodeformable material, previously heated until soft, to penetrate into

said cavities.

The present invention is hereinafter further clarified

in a preferred embodiment with reference to the accompanying

drawings in which:

Figure 1 is a partly sectional diagrammatic side view of a machine for implementing the method according to

Figure 2 is. a front view thereof on the inlet side in the direction II-II of Figure 1 ;

Figure 3 is an enlarged detailed perspective view of two

adjacent pairs of rollers and the corresponding

heater elements;

Figure 4 Is a diagrammatic plan view of a pair of adjacent

presser rollers;

Figure 5 is a plan view from above of a modified embodiment

of a pair of adjacent rollers; and

Figure δ is a plan view from above of a further modifie

embodiment of a pair of adjacent presser rollers.

As can be seen from the figures, the machine fo

implementing the method according to the invention consist

essentially of a continuos press 1 comprising a fixed lowe

bed 2 and a mobile upper structure 3.

At both ends of the press 1 there are provide

conventional roller tables 4 and 5 for feeding an discharging the panels 6 respectively. A plurality of synchronously operates steel rollers

are mounted on the bed 2. Six rollers 7 are shown in th illustrated machine.

The mobile upper structure 3 consists of a support fram

for a like number of rollers 8 disposed parallel to th rollers 7 and facing these latter.

The height of the frame 3 above the bed 2 can b adjusted by pneumatic cylinder-piston units 10.

The rollers 8 are constructed of rubber of differin

hardness which increase from the inlet end roller to th

outlet and roller of the press. In the illustrated example

the hardness of the inlet roller 8 is about 13x Shore, an

the hardness of the outlet roller is about 40x Shore

although these values can vary according to the materials t

be treated and the work to be carried out.

Above the frame 3 and facing each roller 3 there ar

provided pairs of radiant heater elements 9 dispose transversely to the press and extending over the entir length of the corresponding rollers 8.

Between each pair of rollers 7, 8 and the adjacent pair

there are also provided other radiant heater elements 11

secured to the frame 3 and disposed parallel to the heater

elements 9. Finally, other radiant heater elements 12 are provided

above the feed roller table 4.

All the heater elements 9,- 11 and 12 are adjustable in

height and are provided with known poten iometrie devices

which enable their intensity to be varied.

The machine according to the invention operates in the

following manner:

the height of the upper mobile structure 3 above the bed 2 is

adjusted so that the minimum distance between the rollers 7,

3 of each pair is slightly less than the minimum thickness of

the panels 6 to be treated, as measured at their cavities or

grooves. The height and/or intensity of the heater elements

9, 11 and ^r 12 are then adjusted in such a manner as to obtain

increasing temperature both along the roller table 4 and

along the press 1. More specifically:

- the intensity of the heater elements 12 is adjusted in suc

a manner that the temperature along the roller table

increases progressively from ambient to about 30-40xC a

the pair of inlet rollers of the press 1 ;

- the intensity of the heater elements 9 and 11 is adjuste in such a manner that the temperature at the surface of the

rollers 8 and within the press 1 increases progressivel from a value of 30-40:"c at the inlet roller to a value o

about 120 °C at the outlet roller.

The temperature conditions are obviously related to th nature of the cladding material, although in all cases th

outlet temperature of the roller table 4 must substantiall

correspond to the inlet temperature of the press 1 to preven the adhesive and cladding undergoing undesirable therma

shock.

When the machine has been arranged in this manner, th

panels 6 to be treated consisting of a chipboard support, t

the engraved surface of which there has previously bee

bonded a sheet of PVC or other thermode ormable material, ar

disposed on the roller table 4 and fed to the press 1. Durin

this stage the preheating of that panel surface facing th

heater elements 12 results in partial so tening of sai

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cladding layer and the softening of the adhesive which bind

the cladding layer to the chipboard substrate.

As the panel 6 advance along the press 1 , the combine

effect of the temperature, which Increases proressivel

during passage between the adjacent pairs of rollers 7,3 an

softens the PVC sheet together with the pressure exerred b

the rollers 8, which press with their rubber surface against

said softened cladding until they cause it to penetrate into the cavities in the underlying chipboard substrate, is such as to perfectly and faithfully clad the panel surface. '

This operation is also effected gradually because of the

progressively increasing hardness of the rubber of the

rollers 3 which enables the pressure on the cladding material

to be increased while maintaining the pressure with which the

upper stucture 3 is pressed by the cylinder-piston units 10

against the bed constant.

From the aforegoing it is appartent that the method for

forming surface-engraved panels according to the invention

and the machine for implementing the method enable numerous advantages to be obtained and in particular:

- they obviate the need for presses with punches, together

with all their related drawbacks,

— they enable panels engraved with any design to be treated,

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- because of the hardness and elasticity of the rubber laye

of the rollers 8, they enable this layer to completel

penetrate into the cavities formed in the chipboar substrate, with consequent faithful design reproduction,

- they allow continuous working.

In a further embodiment the machine according to th

invention has its upper rollers of rubber, and these instea

of being -constructed in one piece (see the rollers 8 i

figure 4) are constructed as a plurality of segments, whic allow greater penetration in the case of panels with ver

deep cavities. These segments can be arranged either side-by

side with each other (see the rollers 3' in figure 5) o

spaced apart, in which case they are offset from the segment

of the adjacent roller (see the rollers 8" in figure 6).

As it is often necessary to limit the heating effect o

the heater elements 11 to only the width of ^• the chipboar

substrate without heating that cladding portion whic

projects beyond this, according to the invention screens 1

of adjustable distance apart can be provided in corrspondenc

with the heater elements 11 in order to limit the heating o

the panels 6 by said heater elements 11 to the effectiv width of the panel 6.