Apparatus and method for applying thermoplastic spacers to glass sheets

Abstract

An apparatus (20) for applying a thermoplastic spacer (3) to a glass sheet (2 ') comprises a lower support (16) and a lateral support (18) for the glass sheet (2'), a nozzle (10), and associated positioning means (14) for moving the nozzle (10) relative to the sheet (2 '), and supply means (15) for supplying thermoplastic material to the nozzle (10). The apparatus further comprises a pad device (100) positioned to act at a first section (13) of the distributed thermoplastic material having a reduced thickness. The pad arrangement (100) comprises a pad (101) and actuator means (104) adapted to move the pad (101) from a retracted position to an extended position according to an axis (Z) substantially perpendicular to the position of the lateral support (18), in which extended position the pad (101) is adapted to apply pressure at a first section (13) of thermoplastic material distributed onto the glass sheet (2 ').

Description

Field of the Invention

[0001] The present invention relates to an apparatus and method for applying a thermoplastic spacer for insulating glass. In particular, the present invention relates to an apparatus for improving the adhesion of a thermoplastic spacer to a glass plate by eliminating the conventional drawbacks of the prior art application methods. Background Art

[0002] As is well known, insulating glass in the simplest configuration for insulating glass consists of two glass plates separated by a spacer, which can be rigid, i.e., made of a metallic material, a rigid polymeric material, or a mixed metal-polymer material, or the spacer can be flexible, supplied in the form of a roll or ultimately made of a thermoplastic material supplied in a reel and directly extruded onto the glass by an automated machine.

[0003] The present invention relates to the case of using a thermoplastic spacer, for which it is known that the thermoplastic spacer is deposited on a glass plate, subsequently joined to another glass plate, and then the assembly is sealed over the entire peripheral edge portion using a secondary sealant to form a so-called insulating glass.

[0004] It is also known that multiple operations can be involved to obtain, for example, insulating glass consisting of three glass plates and two spacers, and insulating glass consisting of "n" glass plates and "n - 1" spacers.

[0005] For ease of understanding the following disclosure, a brief description of the technical solutions commonly implemented to make insulating glass by applying a thermoplastic material by an automated machine is useful.

[0006] The extrusion of the thermoplastic material according to the manufacturing instructions must occur at a temperature close to 130°C.

[0007] Preferably, when the spacer profile is extruded onto the glass, the cross-section of the spacer profile is rectangular. To ensure sufficient adhesion between the spacer and the glass, it can be stipulated that the application occurs such that the dimension of the strip deposited on the glass in a direction perpendicular to the glass itself is approximately 10% (up to 12%) larger than the desired final dimension, and this height is achieved by the steps of assembling and pressing the insulating glass. Thus, in the final configuration, the cross-section of the spacer adopts a shape in which the sides that do not contact the glass are usually slightly expanded, as shown in the schematic and prominent depiction in Figure 1A.

[0008] One of the technical solutions for creating a connection between the initial and final portions of a strip of thermoplastic material is described in WO96 / 09456, and this is the most used solution by machine manufacturers.

[0009] Referring to FIGS. 2A to 2D which show schematic views of the method of the above-mentioned patent application, the thickness of the thermoplastic material strip 3 extruded by the nozzle 10 increases from an initial zero (FIG. 2A) to a desired thickness (FIG. 2B), and at the end of the application (FIG. 2C), the thickness decreases from the desired thickness to zero (FIG. 2D) in a complementary manner. With this scheme, by using the deposited additional material and then pressing the thermoplastic strip during the assembly of the insulating glass, two inclined and matching surfaces along the inclined plane 11 are obtained, which creates a connection between the head and the tail of the spacer.

[0010] EP0823531A2 discloses a subsequent evolution of the scheme just introduced. This document highlights the weakness of the above-mentioned scheme. On this basis, as seen in FIGS. 3 and 4, at the initial deposition point of the material, there is no good contact with the material deposited in the final step of the process, but a blank area is retained, which is indicated by the reference numeral 12 in FIG. 4. This blank area forms a possible channel for gas and moisture between the interior and the exterior of the insulating glass. This defect is caused by a sudden inclination change between the final deposition area of the thermoplastic material on the glass and the inclined portion of the material deposited according to the inclined plane 11. The scheme proposed in EP0823531A2 shown in FIG. 5 includes: creating an initial section of the thermoplastic material deposition indicated by the reference numeral 13 in the drawing, and then continuing with the inclined portion 11 as already described until the desired thickness is reached. The initial section 13 with a thickness reduction of about dozens of millimeters eliminates the sudden inclination change at the tip 12 of the first deposition section. Nevertheless, a problem still reappears at the starting point of the section 13. At the starting point of the section 13, there is no sudden inclination change of the deposited material, but a thickness change of dozens of millimeters, which is sufficient to produce defects such as channels for gas and moisture.

[0011] Another defect relates to the application process: during extrusion, in order to obtain good adhesion of the thermoplastic material to the glass, a hydrodynamic thrust is used, which is applied to the material towards the glass due to the specific shape of the application nozzle. However, obviously there is no such thrust in the first initial extrusion step of the section 13 in FIG. 5, because when the nozzle starts to open, the material is obviously stationary at first, and due to the absence of flow dynamics, there is no hydrodynamic thrust. In addition, considering that a small amount of material moves along the entire section 13, the hydrodynamic thrust can only be quite small even if it is not completely absent in this section. The result is inconsistent adhesion in the initial part of the section 13, and this section only rests on the glass instead of adhering to the glass.

[0012] In addition, another problem is the difficulty of controlling the extrusion when the amount of material to be processed is reduced, as in the case of section 13. The specific characteristics of the thermoplastic material used do have to be considered, since thermoplastic materials are very sensitive to various factors such as temperature, pressure, shear stress (note that there are so-called non-Newtonian materials, i.e., the viscosity of non-Newtonian materials varies according to shear stress and thus also according to flow rate), etc. In addition to this, first of all, in the practice of starting the extrusion process, a relative movement is applied between the nozzle and the glass, and only after a few minutes is the nozzle commanded to open and the deposition of the material to start. At this point, it is clear that even if only one of the variables involved varies, when the nozzle is opened, the material will react with different behaviors and different delays. All of this results in the control system of the machine not knowing the exact position of the initial part of section 13. When the nozzle approaches the initial section 13 at the end of the travel of the nozzle around the outer periphery of the glass and ends the application method by superimposing the thermoplastic material on the previously deposited thermoplastic material, the nozzle has to move away from the glass by several tens of millimeters to avoid interacting with the material of section 13 and dragging the material away from the glass, thus causing serious defects in the final product. The need to combine with the fact that the control unit of the machine does not know the exact position of the initial point of section 13 makes it almost inevitable to form a passage for gases and water vapor between the outside and the inside of the isolated glass. Even subsequent pressing during assembly cannot eliminate such defects.

[0013] If a subsequent secondary seal is provided, which can reduce the negative impact of such defects and further impede the penetration of moisture and the passage of gases, even if not effective for all the materials used, then the above-mentioned defects are acceptable within certain well-defined limits. On the contrary, if no secondary seal is provided, the consequences are unacceptable, so it is better to look for solutions, such as those described in WO2010111174A1 and shown in Figure 1B, where the spacer made of thermoplastic material also fulfills the function of a secondary seal. Therefore, in this case, any defect on the thermoplastic spacer will directly affect the performance of the final product, since there is no secondary barrier to compensate for such a defect. Summary of the Invention

[0014] Therefore, an object of the present invention is to solve at least in part the drawbacks of the prior art.

[0015] The first task of the present invention is to eliminate the drawbacks of the prior art by means of a device and a method that can allow the extrusion of a thermoplastic spacer without difficulties due to the characteristics of the materials and machines usually dedicated to this process when creating an initial section characterized by a very small thickness.

[0016] At the same time, another task is to eliminate the defects generated at the convergence point of the first segment and the subsequent segments of the strip condition deposited when creating the connection between the head and the tail of the application.

[0017] In such a case, the goal to be achieved is also: to allow the extrusion of the final segment of the thermoplastic spacer without the need to precisely adjust the distance between the nozzle and the glass at the point where the initial segment and the final segment are superimposed in the final processing step.

[0018] Another goal is to ensure optimized adhesion to the glass and optimized adhesion on the first segment of the extruded material.

[0019] Such a need is at least partially achieved by the device for applying a thermoplastic spacer to insulating glass according to claim 1 and the method for applying a thermoplastic spacer to insulating glass according to claim 12. Description of the Drawings

[0020] The additional features and advantages of the present invention will be more readily understood from the following description of the preferred non-limiting embodiments of the present invention, wherein:

[0021] - Figure 1A illustratively shows a cross-section of insulating glass 1 near the outer peripheral edge, highlighting the glass plates 2 and 2', the thermoplastic spacer 3 and the secondary sealant 4;

[0022] - Figure 1B illustratively shows a cross-section of insulating glass 1 near the outer peripheral edge in the absence of the secondary sealant, but the traditional function of the secondary sealant is satisfied by the thermoplastic spacer itself. The glass plates 2 and 2' and the thermoplastic spacer 3 are obvious;

[0023] - Figure 2A illustratively shows a cross-section of the extruder nozzle 10 of the thermoplastic spacer in the case of being close to the glass 2' before the start of the application process;

[0024] - Figure 2B shows the same nozzle after the first part of the spacer 3 has been applied, generating an inclined surface 11;

[0025] - Figure 2C shows the final step of the application process, in which the extruder nozzle 10 is ready to end the connection by superimposing the material in a complementary manner to the material already completed in the start step;

[0026] - In Figure 2D, the connection is completed;

[0027] - Figure 3 shows (circled) the point where the sealing defect of the connection part described in the prior art is located;

[0028] - Figure 4 is an enlarged view of the area of the defect described in the prior art;

[0029] - Figures 5A and 5B illustratively show two steps of a method for applying a thermoplastic spacer;

[0030] - Figure 6A illustratively shows a part of a device for applying a thermoplastic spacer in a side view and in a rest situation;

[0031] - Figure 6B illustratively shows a side view of the device in Figure 6A in an activated situation;

[0032] - Figure 6C illustratively shows a side view of an application performed by a possible embodiment of a device for applying a thermoplastic spacer;

[0033] - Figure 7 A side view of an alternative embodiment of a device for applying a thermoplastic spacer in an activated situation is illustratively shown; and

[0034] - Figure 8 A device for applying a thermoplastic spacer according to a possible embodiment is illustratively shown.

[0035] Elements or parts of elements shared by the embodiments described below will be indicated by the same reference numerals. Detailed Description

[0036] Figure 1A shows a peripheral cross-section of insulating glass, which is composed of two glass plates 2 and 2', a thermoplastic spacer 3, and a secondary seal 4. Obviously, the entire disclosure below is also applicable to the case of manufacturing insulating glass with more than two glass plates and more than one spacer to form more than one chamber. This type of embodiment is not shown but is well-known to those skilled in the art.

[0037] Figure 1B shows a special case where the insulating glass is composed of glass plates 2 and 2' and a spacer 3, and there is no secondary sealant. In this case, the function of the secondary sealant is performed by the spacer itself.

[0038] Figure 8 A device for applying a thermoplastic spacer to a glass plate according to the present invention is shown, which is indicated by the general reference numeral 20.

[0039] The device 20 includes a lower support 16 and a lateral support 18 for the glass plate 2'.

[0040] In addition, the device 20 includes a nozzle 10, associated positioning means 14 for moving the nozzle 10 relative to the plate 2', and supply means 15 for supplying thermoplastic material to the nozzle 10.

[0041] The apparatus 20 includes a padding device 100, and the padding device 100 includes a pad 101 and an actuator device 104. The actuator device 104 is adapted to move the pad 101 from a retracted position to an extended position along an axis Z that is substantially perpendicular to the arrangement of the lateral support 18.

[0042] In the extended position, the pad 101 is adapted to apply pressure at a first section 13 of the thermoplastic material that is distributed onto the glass plate 2'. In other words, the pad 101 is adapted to move closer to (extended position) and away from (retracted position) the lateral support 18, and in the extended position, the pad 101 is at a distance from the lateral support 18 to allow at least part of the amount of the thermoplastic material distributed on the plate 2' supported by the lateral support 18 to be extruded.

[0043] Accordingly, a method for applying a thermoplastic spacer 3 to a glass plate 2' to manufacture insulating glass includes the following steps:

[0044] (a) Applying a first section 13 of the thermoplastic material through a nozzle 10, the first section 13 having a reduced and substantially constant thickness, as seen in the example in FIG. 5A;

[0045] (b) Applying a second section 11, in which the thickness of the thermoplastic material gradually increases from the thickness of the first section 13 to an operating thickness;

[0046] (c) Applying a third section 5, in which the thermoplastic material has an operating thickness;

[0047] (d) Applying a fourth section 6 of the thermoplastic material, the fourth section 6 being substantially superimposed on the first section 13, and the thickness in the fourth section 6 being substantially the same as the thickness in step (c); and

[0048] (e) Applying a fifth section 7, the fifth section 7 being substantially superimposed on the second section 11, and in the fifth section 7, the thickness of the fifth section 7 gradually decreases until the nozzle 10 is closed, such that the sum of the thicknesses of the second section 11 and the fifth section 7 is substantially equal to the operating thickness.

[0049] The method further includes step (f), in which the first section 13 is pressed toward the glass plate 2' by the pad 101 of the padding device 100 in the extended position. Step (f) occurs before step (d).

[0050] In the present disclosure, the term "operating thickness" means the thickness of the thermoplastic material before joining between the glass plates 2 and 2'.

[0051] Figure 6A shows a side view of a device implementing the present invention, where there is a glass 2', at which at least a first section 13 of reduced thickness of the thermoplastic spacer 3 has been deposited. The pad 101 is capable of moving along the axis Z, i.e., perpendicular to the glass plate 2', and then being in a retracted position or a resting position of the pad 101. The actuator 104 is adapted to move the pad 101 forward so that the pad 101 comes into contact with the first section 13 of the thermoplastic spacer 3 (extended position), as shown in Figure 6B.

[0052] Therefore, the pad 101 pushed by the actuator 104 is capable of changing the thickness of the first section 13 of the thermoplastic spacer 3, reducing the thickness to a desired value.

[0053] Advantageously, the pad 101 is covered with an anti-adhesion material 103, such as polytetrafluoroethylene, on the surface of the pad 101 for contacting the thermoplastic material. Thus, it is avoided that the thermoplastic material adheres to the pad 101 during the step of retracting the pad 101 to the retracted position.

[0054] Also advantageously, in order to avoid the thermoplastic material of the first section 13 continuing to adhere to the pad 101, the retraction movement of the pad 101 from the extended position to the retracted position can always be performed very quickly. In fact, the known properties of such materials are thus utilized to slowly adapt to external stresses, and in the case of a sudden separation stress, continue to adhere to the material with greater adhesion usually, without causing the rupture of the material part when the two parts move away from each other because the material part is separated and adheres to the two parts.

[0055] According to a possible embodiment, the actuator device 104 can be adapted to move the pad 101 from the extended position to the retracted position at a speed of at least 5 m / s.

[0056] The abutment 102 can be positioned behind the glass plate 2' and at the pad 101. The abutment 102 is adapted to act substantially along the axis Z in a manner opposing the pad 101 to resist the thrust of the pad 101 on the glass plate 2'.

[0057] According to a possible embodiment, the abutment 102 can include an abutment actuator device 105 for moving the abutment 102 between a retracted position and an activated position, in the activated position, the abutment 102 is close to the pad 101 to support the glass plate 2' from the stress of the pad 101. Thus, the stress on the glass plate is avoided, maintaining the integrity of the glass plate.

[0058] The actuator 105 can be pneumatic or can have other types.

[0059] Alternatively, the abutment 105 is replaced by a series of idler wheels with an axis of rotation parallel to the axis Y. The same device for translating the glass sheet 2' along an axis X perpendicular to the axes Z and Y can also act as an abutment against the thrust of the cushion 101. In fact, it is known that such a translation device consists of a carriage with a coupling system for the glass sheet, the carriage usually consisting of suction cups which, when activated, are able to ensure a sufficient support surface to act as an abutment.

[0060] In addition to moving along the axis Z, the cushion 101 can be provided with means for moving the cushion 101 along the axis Y, for example by means of a second actuator (not shown in the figures), i.e. means for moving along the application direction of the thermoplastic spacer. Such movement is actuated after the cushion 101 has entered the starting position of the cushion 101 and is pressing the thermoplastic material, and such movement is carried out in a direction opposite to the direction of application of the thermoplastic spacer relative to the glass 2'. The movement of the cushion 101 along the direction Y aims to "unroll" the thermoplastic material in order to make the thermoplastic material adhere more evenly to the glass and even further reduce the thickness of the thermoplastic material.

[0061] The actuators 104, 105 and 106 can be of the double-acting pneumatic type or of the single-acting type with spring return or electronic type, and the spring return can also function to quickly reset the actuator 104, as described above.

[0062] The cushion device 100 can include heating means 110, for example heating means 110 adapted to increase the temperature of the operating surface of the cushion 101 up to a temperature of about 130 °C.

[0063] Therefore, the risk of contact with the cushion 101 or with its material can be avoided, which would cause a decrease in the temperature of the thermoplastic material and negatively affect the behavior of the thermoplastic material in subsequent application steps.

[0064] Therefore, the advantages achieved by the present invention are evident.

[0065] First of all, the disadvantages of the prior art are eliminated by the device and method which can allow the extrusion of the thermoplastic spacer to be carried out without difficulties due to the characteristics of the materials and machines dedicated to this process when creating an initial section characterized by a very small thickness.

[0066] At the same time, the defects generated at the convergence point of the first section 13 of the thermoplastic material deposited and the subsequent sections during the creation of the connection between the head and the tail of the application are eliminated.

[0067] In addition, the extrusion of the final section of the thermoplastic spacer is simpler since it is not necessary to adjust too precisely the distance between the nozzle and the glass at the point where the initial section and the final section are superimposed in the final processing step.

[0068] Furthermore, an optimal adhesion of the first section 13 of the extruded material to the glass can also be ensured.

[0069] To meet specific needs, a person skilled in the art may modify the above embodiments and / or replace the described elements with equivalent elements without departing from the scope of the appended claims.

Claims

1. An apparatus (20) for applying a thermoplastic spacer (3) to a glass sheet (2'), said apparatus (20) comprising: Lower support (16) and lateral support (18) for the glass plate (2'), nozzle (10), and associated positioning means (14) for moving the nozzle (10) relative to the plate (2'), and supply means (15) for supplying thermoplastic material to the nozzle (10); Characterized in that the device (20) comprises: Pad means (100) positioned to act at a first section (13) of the thermoplastic material distributed having a reduced thickness, the pad means (100) comprising a pad (101) and actuator means (104) adapted to move the pad (101) from a retracted position to an extended position along an axis (Z) substantially perpendicular to the position of the lateral support (18), in which extended position the pad (101) is adapted to apply pressure at the first section (13) of the thermoplastic material distributed onto the glass plate (2').

2. The device (20) according to the preceding claim, characterized in that, The actuator means (104) is adapted to move the pad (101) from the extended position to the retracted position at a speed of at least 5 m / s.

3. The device (20) according to any one of the preceding claims, characterized in that, The pad (101) is covered with an anti-adhesion material (103) on the surface of the pad (101) for contacting the material of the thermoplastic spacer.

4. The device (20) according to the preceding claim, characterized in that, The anti-adhesion material (103) is polytetrafluoroethylene.

5. The device (20) according to any one of the preceding claims, characterized in that, The device (20) comprises a abutment (102) adapted to act substantially along the axis (Z) in a manner opposing the pad (101) to resist the thrust of the pad (101) on the glass plate (2').

6. The device (20) according to the preceding claim, characterized in that, The abutment (102) comprises an abutment actuator means (105) for moving the abutment (102) between a retracted position and an activated position, in which activated position the abutment (102) is close to the pad (101) to support the glass plate (2') against the stress of the pad (101).

7. The device (20) according to any one of claims 1 to 4, characterized in that, The device (20) comprises a series of idler wheels having a rotational axis parallel to the axis (Y), perpendicular to the axis (Z), and perpendicular to the axis (X) along which the glass plate (2') moves.

8. The device (20) according to any one of the preceding claims, characterized in that, The pad means (100) can comprise a second actuator for moving the pad (101) along the application direction of the thermoplastic spacer but in the opposite orientation.

9. The device (20) according to any one of the preceding claims, characterized in that, The actuator means (104) is of double-acting pneumatic type or single-acting type with spring return or electronic type.

10. The apparatus (12) according to any one of the preceding claims, characterized in that, The pad (101) comprises heating means (110).

11. The device according to the preceding claim, characterized in that, The heating means (110) is adapted to increase the temperature of the surface of the pad (100) up to a temperature of about 130 °C.

12. A method for applying a thermoplastic spacer (3) to a glass plate (2') for manufacturing insulated glass, the method comprising the following steps: (a) Applying a first section (13) of thermoplastic material through a nozzle (10), the first section (13) having a reduced and substantially constant thickness; (b) Apply the second section (11), in which the thickness of the thermoplastic material gradually increases from the thickness of the first section (13) to the operating thickness; (c) Apply the third section (5), in which the thermoplastic material has the operating thickness; (d) Apply the fourth section (6) of the thermoplastic material, which is substantially superposed on the first section (13), and the thickness in the fourth section (6) is substantially the same as the thickness in step (c); and (e) Apply the fifth section (7), which is substantially superposed on the second section (11), and in the fifth section (7), the thickness of the fifth section (7) gradually decreases until the nozzle (10) is closed, such that the sum of the thicknesses of the second section (11) and the fifth section (7) is substantially equal to the operating thickness; It is characterized in that The method includes: Step (f), in which the first section (13) is pressed against the glass plate (2') by the pad (101) of the pad device (100) in the extended position; step (f) is before step (d).

13. The method according to the preceding claim, characterized in that, The actuator device (104) is adapted to move the pad (101) from the extended position to the retracted position at a speed of at least 5 m / s.

14. The method (20) according to any one of claims 12 to 13, characterized in that, The method includes step (g), in which the abutting member (102) is driven, and the abutting member (102) is adapted to act substantially along the axis (Z) in a manner opposing the pad (101) to resist the thrust of the pad (101) on the glass plate (2').

15. The method (20) according to the preceding claim, characterized in that, The abutting member (102) is moved between the retracted position and the starting position by means of the abutting actuator device (105), and in the starting position, the abutting member (102) is close to the pad (101) to support the glass plate (2') from the stress of the pad (101).

16. The method according to any one of the preceding claims, characterized in that, The method includes the following step: after the pad (101) has entered the extended position and the pad (101) is in the step of extruding the thermoplastic material, the pad (101) moves along the axis Y in a direction opposite to the direction of applying the thermoplastic spacer.

Images