Apparatus and method for applying a thermoplastic spacer for insulating glazing

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'). Moreover, the apparatus (20) comprises a nozzle (10) and related positioning means (14) for moving said nozzle (10) with respect to said sheet (2'), and feeding means (15) for feeding said nozzle (10) with thermoplastic material. The apparatus (20) is provided with padding means (100) positioned to act at a junction (120) defined by the initial end (122) and the final end (124) of the distributed thermoplastic material, said padding means (100) comprising a pad (101) and actuator means (104) adapted to move the pad (101) according to an axis (Z) substantially perpendicular to the position of the lateral support (18), from a retracted position to an extracted position in which said pad (101) is adapted to come into contact with the thermoplastic spacer (3) at the junction (120).

Description

APPARATUS AND METHOD FOR APPLYING A THERMOPLASTIC SPACER FOR INSULATING GLAZINGDESCRIPTIONFIELD OF APPLICATION

[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 a device for improving the adhesion of the thermoplastic spacer to a glass sheet and the elimination of a defect of the application method .BACKGROUND ART

[0002] Insulating glass in the simplest configuration thereof consists of two glass sheets separated by a spacer which can be rigid, i . e . , consisting of metal or plastic or mixed metal-plastic material, or flexible supplied on coils , or finally made of thermoplastic material supplied in drums and extruded directly onto the glass by automated machines .

[0003] The present invention relates to the case of use of the thermoplastic spacer, for which its depositing onto a glass sheet is known, and the subsequent coupling to another glass sheet , to then seal the assembly on the entire outer periphery with a secondary sealant to form the so-called insulating glass .

[0004] It is also known that a multiple operation can beinvolved to obtain, for example, an insulating glass consisting of three glass sheets and two spacers , as well as "n" glass sheets and "n-1" spacers .

[0005] In order to easily comprehend the disclosure below it is useful a brief description of the solutions commonly implemented for applying, by means of automated machines , the thermoplastic material for making the insulating glass .

[0006] The extrusion of the thermoplastic material, according to the indication of the manufacturers , 1 must occur at a temperature close to 130 ° C .

[0007] Preferably, the section of the spacer profile, at the time of its extrusion onto the glass , is rectangular, and in order to ensure an adequate adhesion between the spacer and the glass , it is prescribed for the application to occur so that the dimension of the strip deposited onto the glass , in the direction perpendicular to the glass itself , be about 10% (up to 12% ) greater than the final dimension desired, which height is achieved with the steps of assembling and pressing the insulating glass . Therefore, the section of the spacer in the final configuration takes the typical, slightly bulged shape of the sides not in contact with the glass , as shown in the emphasized depiction in Figure 1A .

[0008] One of the technical solutions for creating thejunction between the initial and final parts of the strip of thermoplastic material, and also the most used solution by machine manufacturers , is described in WO96 / 09456 : with reference to Figures 2A-2D, the thickness of the thermoplastic material strip 3 extruded by a nozzle 10 is initially incremented from zero (Fig . 2A) to the desired thickness (Fig . 2B) , and in a complementary manner, at the conclusion of the application (Fig . 2C) , it decreases from the desired thickness to zero (Fig 2D ) . With this solution, by utilising the extra material deposited and the subsequent pressing of the thermoplastic strip during the assembly of the insulating glass , two inclined and matching surfaces along the inclined plane 11 are obtained, which create the junction between the head and the tail of the spacer .

[0009] More in detail, the shape of the upper part of the spacer is convex after the application thereof onto a first glass sheet , as shown in an emphasized manner in Figure 3 . Such a configuration avoids the formation of air bubbles during the assembly with the second glass sheet and the subsequent pressing .

[0010] However, the difficulty in carrying out , in practice, exactly what is shown in Figure 2D is to be considered . Indeed, in the end point of the junction,indicated by reference numeral 15 in Figure 2D, there is the closure of nozzle 10 and the detachment thereof from the material of the spacer . This step often exhibits the tendency for a small part of material, that corresponding to the last amount extruded, to keep adhering to the nozzle, to follow it in the first part of its separation movement , to then be definitively detached . The consequence of all of this is the formation of a small "smudge" which will then be pressed above the material of the spacer in the subsequent as sembly step of the insulating glass . The final result is shown in Figure 4 , where a plan view of a part of the insulating glass is shown . Through the glass sheet 2 , i . e . , that not receiving the thermoplastic material during the extrusion, but that pressed against the spacer already present on sheet 2 ' , can be seen the spacer in the area of the junction . Note the arched shape of area 15 highlighting the presence of an adhesion defect due to the passage from the thickness of the last part of extruded material to the upper surface of the spacer initially deposited . Such a defect is apparent due to the different colouring it takes , tending to be grey, unlike the intense black of the remaining contact area between spacer and glass . It is a preferential passage for gases and moisture entering into the insulating glass .

[0011] The resolution of such a defect by means of suitable settings and the introduction of specific parameters for optimizing the control of the extrusion of the thermoplastic material by the machine in this specific area clashes with the features of the material, which are notoriously very sensitive to several variables , such as : temperature, extrusion pressure, flow rate, viscosity ( it should be kept in mind that these are non-Newtonian materials for which the viscosity varies as the shear stress , i . e . , the flow rate, varies ) , etc . The consequence of this is the risk of needing an intervention on the technological parameters of the machine several times during the same work shift , with significant waste of time and lost productivity .

[0012] The defect described above is acceptable, within certain well-defined limits , if the subsequent secondary sealing is provided, that even if is not as effective for all the materials used, can mitigate the negative effects of such a type of defect and be a further obstacle to the penetration of moisture and passage of gases . The consequences instead are less acceptable, and therefore the need to find a solution is greater, should the secondary sealing not be provided, as described, for example, in W02010111174A1 and shown in Figure IB, where the spacer made of thermoplastic material also fulfilsthe functions of the secondary sealant . Therefore, any defect on the thermoplastic spacer in this case directly affects the performance of the end product since there is no secondary barrier which can make up for such a deficiency .

[0013] An attempt to improve the appearance of the junction as shown above is provided by EP3209842B1 , which discloses a method of vibrationally treating the inner lateral surface of a thermoplastic spacer .OVERVIEW OF THE INVENTION

[0014] Therefore, it is the object of the present invention to at least partially solve the drawbacks of the prior art .

[0015] It is a first task of the present invention to eliminate the drawbacks attributed to the prior art with an apparatus and method capable of allowing the extrusion of the thermoplastic spacer without the concern of creating the conditions for the appearance of defects after the assembly of the end product .

[0016] At the same time, it is also a task to eliminate all irregularities in the point in which the extrusion nozzle is closed to complete the depositing of the thermoplastic spacer .

[0017] In such a context , the aim to be achieved is also to suggest an effective solution without excessivelyaffecting the costs for making it and the cycle time of the production line .

[0018] Such needs are met , at least partially, by an apparatus for applying a thermoplastic spacer onto a glass according to claim 1 , and by a method for applying a thermoplastic spacer onto a glass according to claim 14 .DESCRIPTION OF THE DRAWINGS

[0019] Further features and advantages of the present invention will be more comprehensible from the following description of preferred, non-limiting embodiments thereof , in which :- Figure 1A diagrammatically shows the section of an insulating glass 1 close to the peripheral edge, highlighting the glass sheets 2 and 2 ' , the thermoplastic spacer 3 , and the secondary sealant 4 ;- Figure IB diagrammatically shows the section of an insulating glass 1 close to the peripheral edge if there is no secondary sealant , but the conventional functions of the latter are fulfilled by the thermoplastic spacer itself . The glass sheets 2 and 2 ' and the thermoplastic spacer 3 are apparent ;- Figure 2A diagrammatically shows the section of an extruder nozzle 10 of thermoplastic spacer in the condition of approaching glass 2 ' prior to starting theapplication process ;- Figure 2B shows the same nozzle after the first part of spacer 3 has been applied, with the creation of the inclined surface 11 ;- Figure 2C shows the final step of the application process in which the extruder nozzle 10 is preparing to conclude the junction by superimposing the material in a manner complementary to what was done in the starting step;- in Figure 2D, the junction is completed;- Figure 3 shows the cross section of a thermoplastic spacer deposited onto a glass sheet 2 ' prior to the assembly with a second glass sheet ;- Figure 4 shows the plan view of a portion of insulating glass 1 in the junction area of the thermoplastic spacer 3 , in which a typical defect of the apparatuses and methods of the prior art is apparent ;- Figures 5A and 5B diagrammatically show a portion of an apparatus according to a pos sible embodiment , according to a side view and a front view, respectively;- Figures 6A and 6B diagrammatically show a portion of an apparatus according to a possible embodiment , alternative to the preceding one, according to a side view and a front view, respectively;- Figures 7A and 7B diagrammatically show the portion ofthe apparatus in Figures 5A and 5B in a second operating configuration, according to a side view and a front view, respectively;- Figures 8A and 8B diagrammatically show the portion of the apparatus in Figures 6A and 6B in a second operating configuration, according to a side view and a front view, respectively; and- Figure 9 diagrammatically shows a view of an apparatus for applying a thermoplastic spacer to a glass sheet according to a possible embodiment .DESCRIPTION OF AN EMBODIMENT

[0020] Figure 1A shows the peripheral section of an insulating glass consisting of two glass sheets 2 and 2 ' , a thermoplastic spacer 3 , and a secondary sealant 4 . The entire following disclosure obviously also applies to the cases in which more than two glass sheets and more than one spacer are employed to make insulating glasses with more than one chamber . This type of embodiments is not shown, however they are well known to those skilled in the art .

[0021] Figure IB shows the particular case in which the insulating glass consists of the glass sheets 2 and 2rand the thermoplastic spacer 3 in the absence of the secondary sealant . In this situation, the functions of the secondary sealant are performed by the spacer itself .

[0022] In Figure 9, an apparatus for applying a thermoplastic spacer 3 to a glass sheet 2 ' is indicated by reference numeral 20 .

[0023] Apparatus 20 comprises a lower support 16 and a lateral support 18 for the glass sheet 2 ' .

[0024] Moreover, apparatus 20 comprises a nozzle 10 and related positioning means 14 for moving the nozzle 10 with respect to sheet 2 ' , and feeding means 15 for feeding the nozzle 10 with thermoplastic material .

[0025] As shown in Figure 9, the apparatus 20 comprises padding means 100 positioned to act at a junction 120 defined by the initial end 122 and the final end 124 of the distributed thermoplastic material .

[0026] The padding means 100 comprise a pad 101 and actuator means 104 adapted to move pad 101 according to an axis Z substantially perpendicular to the position of the lateral support 18 , from a retracted position to an extracted position in which pad 101 is adapted to be positioned at a predetermined height , with respect to the glass sheet 2 ' , at junction 120 .

[0027] Figures 5A and 5B show a side view and a front view, respectively, of the padding means 100 , in which there is the glass 2 ' where a thermoplastic spacer 3 was deposited . The pad 101 , movable along axis Z , i . e . , substantially perpendicular to glass ' , is in theresting position ( retracted position) thereof . The actuator 104 is capable of causing the pad 101 (extracted position) to advance up to bringing it into contact with the top of the thermoplastic spacer 3 , at the junction 120 , so as to create the situation shown in Figures 7A and 7B .

[0028] According to a possible embodiment , the actuator means can be of the double-acting pneumatic type or of the single-acting type with a spring return, or of the electric type . Advantageously, the actuator means 104 can be adapted to move the pad 101 from the extracted position to the retracted position at a speed of at least 5 m / s .

[0029] The pad 101 , pushed by the actuator means 104 , is thus capable of modifying the shape of the upper part of the junction 120 of the spacer 3 with which it comes into contact .

[0030] According to a possible embodiment , the pad 101 can be provided with a shaped operating surface 126 . It is thus possible to impart a particular shape to the upper part of junction 120 .

[0031] As shown in Figures 5B, 6B, 7B, and 8B, the operating surface 126 can be shaped to be concave according to a transverse plane with respect to the thermoplastic material distribution direction . The pad101 is thus adapted to impart the desired convex shape to the upper surface of the junction 120 of spacer 3 , as shown in Figure 3 , for example .

[0032] The pad 101 can comprise a layer 102 of antiadhesive material at the operating surface 126 . According to a possible embodiment , the layer 102 of anti-adhesive material can be made of polytetrafluoroethylene or polysiloxane .

[0033] The pad 101 covered with an anti-adhesive material102 on the operating surface 126 intended to come into contact with the material of spacer 3 thus avoids the material itself of the spacer from continuing to adhere with pad 101 when retracting it to the resting ( retracted) position .

[0034] Just as advantageously, the retracting movement of the pad from the active position to the resting position is performed so as to be very quick, always in order to avoid the material of spacer 3 from continuing to adhere to pad 101 . Indeed, there is thus utilised the known property of this type of materials to slowly adapt to external stresses and, in the case of sudden detachment stresses , to keep adhering to the material with which the adhesion is generally greater, without breakages with parts of material which become detached and keep adhering to both parts as they move away .

[0035] According to a possible embodiment , pad 101 can comprise heating means 110 . The heating means 110 can be adapted to increase the temperature of the operating surface 126 of pad 100 up to a temperature of around 130 ° C . The heating means 110 can be, for example, an electrical resistor, in any case, since these are means known per se to those skilled in the art , they will not be further discus sed . Such heating means can also be outside the pad 101 .

[0036] An attempt is thus made to avoid the risk for contact with the pad 101 leading to a lowering in the temperature of the thermoplastic material and negatively affecting the behaviour thereof in the subsequent processing steps . Likewise, should the thermoplastic material be at too low a temperature at the moment of contact with pad 101 , it can be reconditioned to temperature values such as to facilitate the subsequent assembly steps of the insulating glas s .

[0037] According to a possible embodiment , the padding means 100 can comprise a second actuator 108 for moving pad 101 along the thermoplastic spacer application direction y .

[0038] The movement of pad 101 along direction Y aims to "spread" the thermoplastic material to obtain an upper surface of the junction 120 of spacer 3 as homogeneous aspossible .

[0039] According to a possible embodiment , the pad 101 can be of the rotating type . In this case, the pad 101 is a substantially cylindrical body 105 adapted to rotate about a longitudinal axis c thereof substantially parallel to the arrangement of the lateral support 18 so as to be adapted to roll above the junction 120 .

[0040] In this case, the padding means 100 can comprise a support 106 adapted to support a shaft 107 onto which the body 105 is fitted .

[0041] The features of pad 101 in this embodiment remain substantially the same as the preceding embodiment in terms of , for example, the concave shape of body 105 , the heating means , etc .

[0042] In this respect , also in this case, the padding means 100 can comprise a second actuator 108 for moving pad 101 along the thermoplastic spacer application direction .

[0043] In figures 8A and 8B, the body 105 is in the active position (extracted position ) . In this configuration, in addition to the movement along axis Z , the wheel can be also moved along axis Y, parallel to the spacer extrusion direction, by means of actuator 108 . Such a movement is actuated after the body 105 is brought to the active position thereof . The movement of body 105 alongdirection Y aims to "spread" the thermoplastic material to obtain an upper surface of the spacer as homogeneous as possible . To this end, the movement along axis Y can be repeated several times . For example, the body 105 can be moved forward and backward prior to bringing the body 105 back to the resting position ( retracted position) thereof .

[0044] Advantageously, the subsequent passages can be performed with a stroke to the active position in one direction (preferably, the nozzle advancement direction during the extrusion) and with the return in the opposite direction to the retracted position of body 105 .

[0045] Moreover, the subsequent passages can be performed at subsequent heights in direction Z and incrementally up to reaching the desired value . Increased homogeneity and smoothness of the upper surface of the thermoplastic spacer is thus achieved in the junction area .

[0046] According to a possible embodiment , the action of the padding means 100 can be such as to uniform the thickness of the area of the junction 120 to the thickness of the thermoplastic material distributed in other areas .

[0047] The actuator means 104 and the second actuator 108 can be of the double-acting pneumatic type or of the single-acting type with a spring return, or of theelectric type, or in an electric and pneumatic combination .

[0048] Advantageously, with reference to Figure 9, the padding means 100 can be provided with their own positioning means , for example along axes perpendicular and parallel to the lateral support 18 , to be positioned at the area of the junction 120 . Equally advantageously, such a positioning can be performed by taking advantage of the glass sheet movement means and / or the positioning means 14 of the extruder nozzle 10 . Such positioning means are not shown and described, but are well known to those skilled in the art .

[0049] The method for applying a thermoplastic spacer 3 to a glass sheet 2rfor making an insulating glass according to the present invention is described below .

[0050] The method essentially comprises the following steps :(a) distributing thermoplastic material in the form of a strip, comprising an initial end 122 and a final end 124 , in which the final end 124 is superimposed on the initial end 122 to form a junction 120 ;(b) driving the padding means 100 to move the pad 101 by the actuator means 104 from the retracted position to the extracted position at a predetermined height along Z at junction 120 ; and( c) driving the padding means 100 to move the pad 101 by the actuator means 104 from the extracted position to the retracted position .

[0051] The possibly achievable advantages by means of the apparatus and method of the present invention are now apparent .

[0052] Firstly, the drawbacks attributed to the prior are eliminated, allowing the extrusion of the thermoplastic spacer without being concerned about creating the conditions for the appearance of defects after the assembly of the end product .

[0053] At the same time, the irregularities are eliminated in the point in which the extrusion nozzle is closed to complete the depositing of the thermoplastic spacer .

[0054] Moreover, an effective solution is suggested, which does not affect the costs for making the insulating glass or the cycle time of the production line .

[0055] Again, it is possible to correct the so-called "smudge" due to the permanent detachment by the nozzle with respect to the distributed thermoplastic material .

[0056] In order to meet specific needs , those skilled in the art may make changes to the embodiments described above and / or replace the elements described with equivalent elements without departing from the scope of the appended claims .

Claims

CLAIMS1. Apparatus (20) for applying a thermoplastic spacer (3) to a glass plate (2' ) comprising a lower support (16) and a lateral support (18) for said glass plate (2' ) , a nozzle (10) and relative positioning means (14) for moving said nozzle (10) with respect to said plate (2' ) , and feeding means (15) for feeding said nozzle (10) with thermoplastic material; characterised in that it comprises padding means (100) positioned to act at a junction (120) defined by the initial end (122) and the final end (124) of the distributed thermoplastic material, said padding means (100) comprising a pad (101) and actuator means (104) adapted to move said pad (101) according to an axis (Z) substantially perpendicular to the position of said lateral support (18) , from a retracted position to an extracted position in which said pad (101) is adapted to come into contact with the thermoplastic spacer (3) at a predetermined height along Z with respect to said glass sheet (2' ) at the junction (120) .

2. Apparatus (20) according to the preceding claim, characterised in that the actuator means (104) are of the double-acting pneumatic type or single-acting with spring return, or of the electric type, or combined electric and pneumatic .

3. Apparatus (20) according to any one of the preceding claims, characterised in that said actuator means (104) are adapted to move the pad (101) from said extracted position to said retracted position at a speed of at least 5 m / s.

4. Apparatus (20) according to any one of the preceding claims, characterised in that said pad (101) is arranged with a shaped operating surface (126) .

5. Apparatus (20) according to the preceding claim, characterised in that said operating surface (126) is shaped to be concave according to a transverse plane with respect to the distribution direction of the thermoplastic material.

6. Apparatus (20) according to any one of the preceding claims, characterised in that said pad (101) comprises a layer of anti-adherent material (102) at the operating surface (126) .

7. Apparatus (20) according to the preceding claim, characterised in that said layer of anti-adhesive material (102) is made of polytetrafluoroethylene or polysiloxane .

8. Apparatus (20) according to any one of the preceding claims, characterised in that said pad (101) comprises heating means (110) .

9. Apparatus (20) according to the preceding claimcharacterised in that said heating means (110) are adapted to increase the temperature of the operating surface (126) of the pad (100) up to a temperature around 130°C.

10. Apparatus (20) according to any one of the preceding claims, characterised in that the pad (101) is of the rotating type.

11. Apparatus (20) according to the preceding claim, characterised in that said rotating pad (101) comprises a substantially cylindrical body (105) , adapted to rotate around a longitudinal axis (c) thereof, said longitudinal axis (c) being substantially parallel to the arrangement of the lateral support (18) , and being adapted to roll above the distributed thermoplastic material.

12. Apparatus (20) according to the preceding claim, characterised in that said padding means (100) comprise a support (106) adapted to sustain a shaft (107) on which said body (105) of said pad (101) is keyed.

13. Apparatus (20) according to any one of the preceding claims, characterised in that said padding means (100) comprise a second actuator (108) for moving said pad (101) along the application direction of the thermoplastic spacer.

14. Method for applying a thermoplastic spacer (3) to a glass plate (2' ) for making an insulating glass,comprising the steps of:(a) distributing thermoplastic material in the form of a strip, comprising an initial end (122) and a final end (124) , said final end (124) being superimposed on said initial end (122) to form a junction (120) ;(b) driving the padding means (100) to move the pad (101) by means of the actuator means (104) from the retracted position to the extracted position in which said pad (101) is adapted to come into contact with the thermoplastic spacer (3) at a predetermined height along the axis Z with respect to the glass sheet (2' ) at the junction (120) ; and(c) driving the padding means (100) to move the pad (101) by means of the actuator means (104) from the extracted position to the retracted position.

15. Method according to the preceding claim, characterised in that said actuator means (104) are adapted to move the pad (101) from said extracted position to said retracted position at a speed of at least 5 m / s.

16. Method according to any one of claims 14-15, characterised in that it comprises a step in which the pad (101) is moved along the axis Y thanks to the second actuator (108) , along the application direction of the thermoplastic spacer, after the pad (101) has beenbrought into the extracted position and is in the process of contact with the thermoplastic spacer (3) .

17. Method according to any one of claims 14-15, characterised in that it comprises a step in which the body (105) is rolled along the axis Y, after the body (105) has been brought into the extracted position and is in contact with the thermoplastic spacer (3) .

18. Method according to the preceding claim, characterised in that the body (105) is rolled along the axis Y with successive back and forth passes and in extracted position.

19. Method according to claim 17, characterised in that the body (105) is rolled along the axis Y with successive back and forth passes, from a partially extracted position to a completely extracted position of the body (105) , so as to gradually reach the desired thickness value of the distributed thermoplastic material.

20. Method according to claim 17, characterised in that the body (105) is rolled along the axis Y with successive passes, in the extracted position of the body (105) along one direction, preferably that of advancement of the nozzle (10) during the application of the thermoplastic material, and with the return in the opposite direction in the at least partially retracted position of the body(105) .

21. Method according to claim 17, characterised in that the body (105) is rolled along the axis Y with successive passes, from a partially extracted position to a completely extracted position of the body (105) along one direction, preferably that of advancement of the nozzle (10) during the application of the thermoplastic material, and with the return in the opposite direction in the at least partially retracted position of the body (105) , so as to gradually reach the desired thickness value of the distributed thermoplastic material.

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