ITMO20120201A1 - METHOD AND DEVICE FOR WELDING PROFILES IN PLASTIC MATERIAL, IN PARTICULAR PVC - Google Patents

Description

"METHOD AND DEVICE FOR WELDING PROFILES IN PLASTIC MATERIAL, IN PARTICULAR PVC"

DESCRIPTION

The present invention relates to a method and relative device for welding plastic profiles, in particular PVC.

In the known art, the PVC profiles, mostly used as window frames, are welded together by fusion of respective end surfaces in order to create a frame structure applicable to doors or windows. In particular, the fusion takes place by heating the portions to be connected by means of suitable plates with electric resistances and then pressing the heated portions against each other to favor their fusion.

Generally, the heated portions are the head ends of the profiles, suitably cut at 45 ° to define, for example, a right-angled portion of a respective window or door.

This method is implemented by welding machines equipped with respective members for holding the sections, movable in reciprocal approach to bring the heated ends to be welded into contact.

These machines are also equipped with finishing systems, designed to remove the weld bead or bead that is formed during the fusion of the two profiles.

In fact, in correspondence with the joining line of the two profiles (surfaces cut at 45 °), the portion of excess molten material emerges and forms a bead protruding from the visible surface of the profiles. For this reason, in order to give the finished window an appreciable aesthetic appearance, the profiles, once welded, undergo a bead removal process.

However, the known and briefly described welding devices have important drawbacks mainly linked to the formation of the aforementioned welding seam.

In fact, it should be considered that the welding area of the PVC profiles is not completely homogeneous and therefore, to make the profiles regular, a lot of material is melted with the consequent formation of an abundant bead, and therefore an abundant waste material that must be removed.

Furthermore, the finishing processes suitable for removing the bead and cleaning the welding area significantly affect the overall processing times of the window or door. In fact, it should be noted that for each welding of the window, the profiles must be subsequently machined. Furthermore, for rounded profiles, the removal of said bead is considerably complicated. Furthermore, the machines used for the aforementioned finishing operations are bulky and particularly expensive.

This entails the need to sustain additional costs and processing times, also given the presence of additional bulky equipment and tools.

In this context, the technical task underlying the present invention is to propose a method and relative device for welding plastic profiles, in particular PVC, which overcomes the aforementioned drawbacks of the known art.

In particular, it is an object of the present invention to provide a method and relative device for welding two plastic profiles, in particular PVC, capable of eliminating all subsequent additional operations suitable for removing the welding bead.

A further object of the present invention is to propose a method for welding plastic profiles, in particular PVC, which is fast and with limited spaces.

The specified purposes are substantially achieved by a method and relative device for welding plastic profiles, in particular PVC, comprising the technical characteristics set out in one or more of the attached claims.

Further characteristics and advantages of the present invention will become clearer from the indicative, and therefore non-limiting, description of a preferred but not exclusive embodiment of a method and relative device for welding plastic profiles, in particular PVC, as illustrated in the united drawings in which:

- figures la and lb show perspective and schematic views of a one-head device (the heads can be replicated on machines that simultaneously work 4-6 corners) for welding plastic profiles, in particular PVC, for the implementation of the method according to the present invention;

- figures 2a, 2b and 2c show details of the device of figures la and 1b in respective operating conditions;

Figure 3 shows a detailed view of a further operating sequence; - figures 4 and 5 show PVC profiles during the phases of mutual approach;

- Figures 6a and 6b schematically show two successive phases of the traditional execution of the welding of the ends of profiles, in particular the compression phase in which the formation of the curbs is highlighted on both sides: internal and external ;

- figures 7a and 7b schematically show two successive phases of a possible execution of the welding of the ends of the profiles according to a methodology that is not part of the patent and in which the containment of the curbs inside a compartment is highlighted open containment and only on the internal sides of the profiles, ie on the sides delimiting the internal space of the profile;

- figures 8a, 8b, 8c and 8d schematically show four successive phases of the execution of the welding of the ends of the profiles according to the patent in which the formation of a containment barrier defined by the juxtaposition of an edge is highlighted recessed and of a raised edge and which determines the formation of the curbs only on the internal sides of the profiles, that is on the sides delimiting the internal space of the profile;

- Figures 9a and 9b show, in front view, the heated plate heat-sealing element of Figure 8b in two different operating positions.

With reference to the attached figures, 1 indicates a device for welding plastic profiles, in particular PVC.

This device implements a method for welding plastic profiles, in particular PVC, in which at least two profiles 3 are arranged, with respective areas to be welded 4 facing each other.

In the remainder of the present description, a single welding device 1 will be illustrated, suitable for welding the ends of two respective sections. However, the present invention can comprise a series of devices 1, each of which operating on a respective end of a section 3. For example, to make a rectangular frame usable as a window or door, four devices 1 are arranged, each designed to weld the sections 3. at right angles of the aforementioned frame. With reference to Figure 1, it should be noted that the device 1 comprises a pair of retaining members 2 of respective PVC profiles 3, adapted to engage the profiles 3 themselves with corresponding areas to be welded 4 facing each other.

In particular, each retaining member 2 comprises a base portion 5 on which the section 3 is positioned, and a movable portion 6 arranged above the base portion 5. The movable portion 6 is suitably moved (in a known and therefore not described in detail) to move towards the base portion 5 and thus retain the profile 3.

As can be seen in the accompanying figures, each section 3 is therefore arranged between the base portion 5 and the mobile portion 6, with the respective head end protruding. The head ends of the profiles constitute the areas to be welded 4 and for this reason they are counterfaced.

It should also be noted that the areas 4 to be welded are suitably cut at 45 ° to define a coupling between two right-angled sections.

Furthermore, the device 1 comprises means 7 for moving the retaining members 2, for moving the sections 3 between a first position of mutual separation and a second position of mutual approach in which the areas to be welded 4 are coupled together.

In particular, the handling means 7 have for each retaining member 2 a sliding guide 8, extending parallel to the longitudinal development of the section 3. A carriage 9 is mounted on the sliding guide, integral with the aforementioned base portion 5. Furthermore, each carriage 9 is coupled to a movement system 10 (not described in detail as it is of a known type and not part of the present invention) able to move both carriages 9 of the retaining members 2 towards / away from each other.

The device 1 also comprises heating means 11 for the aforementioned areas to be welded 4 of the PVC profiles 3. The heating means 11 are preferably movable between an active condition in which they are interposed between the sections 3, and a condition of non-use in which they are moved away from the sections 3.

It should be noted in particular that when the sections 3 are arranged by the moving means 7 in mutual distance, they define a passage area for the heating means 11. In this way, once the zones to be welded 4 have been heated, the sections 3 are brought closer together. of them and pressed with the respective heads of extremities against each other.

Advantageously, the heating means 11 have a heat-sealing element with a heated plate 12, consisting for example of an electrical resistance having a substantially plate-like conformation, mounted on a movement element 13. Preferably, the movement system 13 consists of a a pair of carriages 14 slidably mounted on respective rails 15 and each of which arranged on opposite sides of the aforementioned resistance 12. In this way, the resistance 12 is anchored to the carriages 14 and moved by them along the rails 15. The carriages 14 are also operatively connected to an engine 16, by means of a connecting rod-crank 17. Advantageously, the crank connecting rod 17 transforms the rotary motion imposed by the engine 16 into a back and forth motion of the carriages 14 and of the resistance 12 to activate / deactivate the resistance electric 12 between / from the aforementioned sections 3.

The device 1 is also equipped with removal means 18 for making at least one groove 19 on a peripheral edge of at least one area to be welded 4.

The device 1 shown in Figures 1 to 3 is capable of making a groove 19 on each of the sections 3 and implementing the method schematically shown in Figures 7a and 7b.

It is easy to understand, however, that the same device 1 can also be used to make the groove 19 only on one of the sections 3 and to put into practice the method illustrated in figures 8a, 8b, 8c and 8d, as will be better described below. .

The removal means 18, for example, are of the milling type and comprise a support frame 20 placed above the retaining members 2, and at least one machining tool 21, facing a section 3 to create the area to be welded 4 the aforementioned groove 19. The tool 21 is moved by a motor member 22 preferably of the electric and miniaturized type, sensorless brushless motor at very high rotation speeds.

Furthermore, the tool 21 is moved by a handling body 23, between a first rest condition (position in which it is not interposed between the profiles 3) and a second machining condition in which it is interposed between the profiles 3 in PVC.

In greater detail, the removal means for milling 18 preferably comprise a pair of machining tools 21, each of which equipped with a head 21 a active on the peripheral edge of a respective area to be welded 4.

As shown in the detailed views, the tools 21 are opposed to each other to work simultaneously on both profiles 3.

Furthermore, the frame 20 is equipped with a support bar 24 arranged above the retaining members 2 and arranged to support the tools 21 which in this situation are mounted on a lower end of the bar 24 itself.

The bar 24 is operatively connected to the handling body 23 to be moved in correspondence with the areas to be welded 4.

Advantageously, the tools 21 are positioned in correspondence with the lateral edge of the zone 4 by means of the movement of the aforementioned moving body 23.

In particular, the body 23 comprises a pair of support guides 25 on which the bar 24 is slidably mounted and moved by a known motor which is not described in detail.

Furthermore, the bar 24 is moved vertically by means of an axis with an endless screw arranged in correspondence with the frame 20.

Advantageously, both the tools 21 and the motor member 22 are supported by the bar 24 and movable with it both horizontally (along the guides 25) and vertically (by means of the worm screw 26).

The device 1 is also equipped with a containment press 27 movable along a direction transverse to the direction of movement of the sections 3, to abut on the grooves 19 made in the respective areas to be welded. This presser can be brought up to temperature to better shape the underlying plastic material and can have protrusions or recesses to reproduce a particular shape on the hot piece just worked. In fact, the still hot material is easily moldable.

In particular, when the grooves 19 are made on both the profiles 3 (method of Figures 7a and 7b) and are arranged in the welded condition of the zones 4, that is to say when the profiles 3 are brought into contact and pressed against each other. the other, the grooves 19 mutually define a containment compartment 19a.

This compartment 19a is also delimited by the containment presser 27 which avoids the leakage of molten material outside the compartment 19a.

Preferably, two containment pressers 27 are provided, each of which can be associated with a respective pair of opposite grooves 19 to define two containment compartments 19a for respective weld seams or seams.

In particular, a first presser 27 is arranged above the sections, while a second presser 27 is arranged below the sections 3.

In fact, it should be noted that the grooves 19 are applied for the externally visible portions of the sections 3, that is to say the lateral edges cut at 45 ° which, when welded together, determine the formation of a protruding weld bead.

In this situation, the cord does not protrude from the compartment 19a but is contained within it.

In this context, the pressers 27 are movable by means of suitable movement elements not described in detail and capable of bringing the pressers 27 closer to / away during the various welding phases of the sections 3..

The device 1 is also equipped with a suction system 29a, 29b with a concentric vortex to the tool 21 which allows to remove the chip forming during the milling removal operation.

The suction system 29a, 29h, for example, consists of a chamber 29a which is arranged around each tool 21 and which is connected to a suction duct 29b which removes the chip.

For this purpose, moreover, the tool 21 consists of a helical cutter which conveys the removed chip towards the interior of the chamber 29a to facilitate its suction.

Advantageously, all the PVC rubbers generated by the milling removal operations are easily aspirated.

The device 1 described above in mainly structural terms, implements a welding method object of the present invention.

The method comprises the steps of providing at least two sections 3, arranged with the respective areas to be welded 4 facing each other, in correspondence with the retaining members.

Subsequently, at least one groove 19 is made in correspondence with at least one zone 4 of the sections 3 to be welded.

Thereafter, the areas 4 to be welded are heated and coupled together by pressing the sections 3 against each other. In this way the areas 4 are kept in mutual contact to melt the areas 4 together thus defining a weld bead.

As previously anticipated, in the solution schematically illustrated in Figures 7a and 7b the grooves 19 are made on both profiles 3 and define the containment compartment 19a inside which the welding seam is retained by means of the presser 27. that when the sections 3 are brought closer together, the grooves 19 coincide with each other to define the compartment 19a, which is open and has a side facing outwards which remains substantially accessible. The presence of the presser 27 causes a closure of the compartment 19a which keeps the welding bead on the same plane as the external visible surfaces of the sections 3.

The step of making the groove 19 is carried out by means of a material removal operation on the peripheral edges defined by the head ends of each section 3. In this way, the groove 19 obtained has a substantially squared step conformation, that is, shaped at 90 °, which extends along the entire development of the area to be welded 4. Prior to the heating phase of the areas to be welded 4, and in particular during the removal phase by milling, the chip holding phase is carried out by means of the helical cutter tool 21 and axial suction which conveys the removed chip towards the inside of chamber 29a.

With reference to the solution shown in figures 8a, 8b, 8c and 8d, on the other hand, the groove 19 is made only on one of the sections to be welded. For this purpose it is possible to divide the sections into a first section 3a, on which the groove 19 is made, and in a second section 3b, on which, on the other hand, the groove 19 is not formed.

The step of making the groove 19 shapes the area to be welded 4 of the first section 3a so as to define a head surface 40 and a recessed edge 41 obtained on a visible surface portion 42 of the first section 3 a.

As in the previous case, also in the solution shown in Figures 8a, 8b, 8c, 8d the step of making the groove 19 is carried out by means of a removal operation on a peripheral edge of the first section 3 a. Subsequently to the step of making the groove 19, a heating operation of the areas to be welded 4 is carried out, which is carried out by approaching the sections 3 a, 3b to the heated plate heat-sealing element 12.

During this phase, a sub-phase is carried out which consists in melting the head surface 40 of the first section 3a and only a part of the area to be welded 4 of the second section 3b, so as to define a recessed surface 43 of the second section 3b and an edge in relief 44 obtained on a visible surface portion 42 of the second section 3b.

For this purpose, in the solution shown in Figures 8 a, 8b, 8c and 8d, the heated plate thermo-welding element 12 is provided with a first face 45, able to come into contact with the head surface 40 of the first section. 3a, and a second face 46, 47, adapted to come into contact only with a part of the area to be welded 4 of the second section 3b. More in detail, the second face 46, 47 comprises at least a protruding part 46, adapted to come into contact with the second section 3b to define the re-entering surface 43, and at least a re-entering part 47, capable of remaining spaced from the second section 3b and to avoid coming into contact with the raised edge 44.

As clearly visible in figure 8b, the second face 46, 47 has two recessed parts 47 which intervene on opposite sides of the second section 3b. The distance h between the recessed parts 47 depends on the height of the second section 3b; the greater the height of the second section 47, in fact, the greater the distance between the recessed parts 47 must be.

For this purpose, the heated plate heat-sealing element 12 can be divided into at least two sections 12a, 12b which are mutually movable to bring the recessed parts 47 closer to and away from each other.

In the embodiment shown in Figures 9a and 9b, for example, each section 12a, 12b is wedge-shaped and has an inclined plane 50 which can slide on the inclined plane 50 of the other section 12a, 12b to vary the distance h between the falling parts 47.

However, alternative equivalent solutions are not excluded such as, for example, the case in which the second face 46, 47 consists of a kit of interchangeable plates, shaped differently from each other (in particular they have different distances h) and can be associated selectively to the heated plate heat-sealing element 12 based on the height of the second section 3b

After the heating phase, the coupling phase of the areas to be welded 4 is carried out, which consists in bringing the sections 3a, 3b together along the sliding guides 8 and which involves the sub-phase of melting the zones 4 together to define the aforementioned weld seam.

In light of the specific conformation of the re-entering edge 41, of the raised edge 44, of the head surface 40 and of the re-entering surface 43, during the coupling step the sub-steps of: melting together the head surface 40 and the recessed surface 43; and approaching the recessed edge 41 and the raised edge 44 in a substantially mating manner without substantially melting them, to define a confinement barrier for the welding seam.

In this regard, it is emphasized that, after the heating phase and prior to the coupling phase of the sections 3a, 3b, the recessed edge 41 of the first section 3a is arranged at a first predetermined distance 48 from the plane of the head surface 40. of the first section 3 a.

Similarly, after heating and before coupling, the raised edge 44 of the second section 3b is arranged at a second predetermined distance 49 from the plane of the recessed surface 43 of the second section 3b.

Conveniently, the first predetermined distance 48 is greater than or equal to the second predetermined distance 49 and, preferably, is slightly greater, so that at the moment of coupling the profiles 3a, 3b, the head surface 40 and the recessed surface 43 come into contact and merge with each other, while the recessed edge 41 and the raised edge 44 simply rest against each other without merging.

The first predetermined distance 48 and the second predetermined distance 49 are established on the basis of the quantity of plastic material to be melted during the coupling step of the sections 3a, 3b.

It is also emphasized that the molten plastic material at the head surface 40 and the recessed surface 43 remains contained within the containment barrier defined by the recessed edge 41 and the raised edge 44 and has no way of surfacing at the exterior of the profiles 3 a, 3b on their visible surface portions 42.

It is therefore easy to understand that in this solution the intervention of the containment pressers 27 is not necessary.

However, the possibility of using the containment pressers 27 resting on the profiles 3 a, 3b is not excluded even in the case shown in figures 8a, 8b, 8c and 8d in order to contain any spillage of the molten material through the corner. re-entrant 41 and the raised edge 44. The present invention achieves the proposed objects. In particular, the possibility of realizing a containment barrier defined by the juxtaposition of the recessed edge 41 and the raised edge 44 prevents excess material from escaping. Consequently, all the surface finishing processes aimed at removing excess material are eliminated, with the consequent advantages in terms of time, energy and savings in the use of additional machinery.

Furthermore, the removal operation guarantees a leveling of the surfaces of the sections 3 in mutual contact, with the consequent saving of the material which at present must be melted to obtain the desired size.

Claims (10)

CLAIMS 1) Method for welding plastic profiles, in particular PVC, comprising the steps of: providing at least two plastic profiles (3 a, 3b), arranged with respective areas to be welded (4) facing each other; heating said areas to be welded (4); coupling together the areas to be welded (4) by pressing the profiles (3 a, 3b) against each other to keep the areas (4) in mutual contact; said step of coupling the areas to be welded (4) defining a sub-step of melting the areas (4) together to define a weld bead; characterized by the fact that: said sections (3a, 3b) comprise a first section (3a) and a second section (3b); said method comprises, prior to the heating step, the step of making a groove (19) in correspondence with the area to be welded (4) of said first section (3 a) to define a head surface (40) and at least one recessed edge (41) obtained on a visible surface portion (42) of said first section (3 a); said heating phase comprises the sub-phase of melting said head surface (40) of the first section (3 a) and a part of the area to be welded (4) of said second section (3b) to define a recessed surface (43) of said second profile (3b) and a raised edge (44) obtained on a visible surface portion (42) of said second profile (3b); And said coupling step comprises melting together said head surface (40) and said recessed surface (43) and approaching said recessed edge (41) and said raised edge (44) in a substantially mating manner without substantially melting them, to defining a confinement barrier for said weld bead. 2) Method according to claim 1, characterized in that said step of making the groove (19) is carried out by means of a removal operation on a peripheral edge of said first section (3a). 3) Method according to claim 2, characterized in that said removal determines a step of said peripheral edge, extending along the entire development of the area to be welded (4) of said first section (3 a). 4) Method according to one or more of the preceding claims, characterized in that, prior to said coupling step, said recessed edge (41) of the first profile (3 a) is arranged at a first predetermined distance (48) from the arrangement of said head surface (40) of the first section (3a). 5) Method according to one or more of the preceding claims, characterized in that, prior to said coupling step, said raised edge (44) of the second profile (3b) is arranged at a second predetermined distance (49) from the arrangement of said recessed surface (43) of the second section (3b). 6) Method according to claims 4 and 5, characterized in that said first predetermined distance (48) is greater than or equal to said second predetermined distance (49). 7) Device (1) for welding plastic profiles, in particular PVC, comprising: - a pair of retaining members (2) of respective sections (3a, 3b), to engage said sections (3a, 3b) with corresponding areas to be welded (4) facing each other; - heating means (1 1) of said areas to be welded (4) of the sections (3 a, 3b), movable between an active condition in which they are interposed between said sections (3) and a non-use condition in which they are removed from said sections (3 a, 3b); means (7) for moving said retaining members (2) for moving the sections (3a, 3b) between a first position of mutual distancing and a second position of mutual approach in which the areas to be welded. (4) are coupled together; characterized by the fact that: said sections (3 a, 3b) comprise a first section (3 a) and a second section (3b); said device (1) comprises removal means for making at least one groove (19) on a peripheral edge of at least one area to be welded (4) of said first section (3 a) to define a head surface (40) and at least one recessed edge (41) obtained on a visible surface portion (42) of said first section (3a); And said heating means (11) comprise at least one heated plate heat-sealing element (12) provided with a first face (45) able to come into contact with said head surface (40) of the first section (3a) and a second face (46, 47) adapted to come into contact only with a part of the area to be welded (4) of said second section (3b) to define a recessed surface (43) of said second section (3b) and a raised edge (44 ) obtained on a visible surface portion (42) of said second profile (3b), said profiles (3a, 3b) being coupled to each other with said head surface (40) and said recessed surface (43) fused together and said re-entering edge (41) and said raised edge (44) approached in a substantially mating way without being substantially fused, to define a confinement barrier of said weld bead. 8) Device (1) according to claim 7, characterized in that said second face (46, 47) comprises at least a protruding part (46) adapted to come into contact with said second profile (3b) to define said recessed surface (43 ). 9) Device (1) according to claim 7 or 8, characterized in that said second face (46, 47) comprises at least a recessed part (47) able to remain spaced from said second profile (3b) and to avoid entering contact with said raised edge (44). 10) Device (1) according to claim 9, characterized in that said second face (46, 47) comprises at least two of said recessed parts (47) and said heated plate heat-sealing element (12) is divided into at least two mutually movable sections (12a, 12b) to bring said recessed parts (47) closer to and away from each other.