Device for and method of aligning and/or maintaining a side of a spacer frame in alignment during fabrication of a multi sheet glazing unit

Abstract: In the manufacture of an insulating unit, a spacer frame having a U-shaped cross section has one leg adhered to marginal edges of a first glass sheet (52) by a layer of a moisture-impervious sealant. An elongated side of the spacer frame adhered to the glass sheets moves out of alignment i.e. the plane (56) containing the base of the spacer frame and the plane containing the major surface of the first sheet (52) are not perpendicular to one another. Magnetic forces are applied to the base to maintain the elongated side of the spacer frame in alignment. Thereafter, a second glass sheet is adhered to the other outer leg (20) of the spacer frame by a layer of moisture impervious sealant (34).

Description: FIELD OF THE INVENTION This invention relates to the manufacture of a glazing unit, and more particularly, to a method of aligning and/or maintaining one or more sides of a spacer frame in alignment during fabrication of a multi sheet glazing unit. DISCUSSION OF RELEVANT ART AND TECHNICAL PROBLEMS European Patent Application Publication No. 0 475 213 A1 published 18.03.92 in Bulletin 92/12 (hereinafter "EP Application") based on U.S. Patent Application Serial Nos. 578,696 and 578,697, each filed September 4, 1995, and 686,956 filed April 18, 1991, discloses a low thermal edge multi sheet glazing unit having glass sheets separated by an edge assembly. The edge assembly includes, among other things, a metal spacer frame having a pair of upright legs spaced from one another and only interconnected by a base to provide the upright legs and base of the spacer with a generally U-shaped cross section. A moisture impervious sealant is provided on outer surfaces of the upright legs, and optionally on the outer surface of the base, and a moisture pervious adhesive having a desiccant therein is provided on the inner surface of the base. In the fabrication of an insulating unit e.g. of the type disclosed in the EP Application, one of the upright legs of the spacer frame is adhered to marginal edge of one of the outer sheets by the sealant; thereafter, the other sheet is positioned on the other upright leg of the spacer frame and adhered thereto by the sealant. The sheets are biased toward one another to flow the sealant to seal the airspace between the sheets. Prior to positioning the second sheet on the sealant of the upright leg of the spacer frame, the side(s) of the spacer frame when of extended length has (have) a tendency to slump when the unit is being fabricated with the glass sheets in a generally vertical position and to bend inwardly when the unit is being fabricated with the glass sheets in a generally horizontal position. As can be appreciated, prior to positioning the second sheet on the second upright leg of the spacer frame, the side(s) of the spacer frame should be aligned e.g. the base of the spacer frame should be generally perpendicular to the adjacent surface of the glass sheet to obtain a proper seal and desired aesthetics. It would be advantageous therefore to provide a technique to align the sides of the spacer frame with the glass sheet(s) during fabrication of the insulating unit. A method and an apparatus to align a spacer frame in a multi sheet unit is disclosed in FR-A-2 219 128. The apparatus comprises a production table running horizontally on a transfer track. Thereon a first sheet of the unit is mounted and afterwards provided with the spacer frame which is placed thereon. Bellcrank arms are moved to the corners of the first sheet, placed against the edges of the sheet and buffers engage the surface of the sheet and bring the spacer frame into alignment. Afterwards holding elements are placed in contact with the spacer frame so that relatively long profiles are secured against displacement and deflection at that zone. Thereafter a second sheet is placed on the spacer frame, the aligning of this sheet is done by swinging up a support element displacing the sheet in the course of its pivoting motion. After alignment a clamping device is applied to hold and secure the unit such that the mentioned accessories can be moved in their inoperative positions and that the unit can be transferred to a bending station to stuck the unit together. BRIEF DESCRIPTION OF THE DRAWING Figure 1 is an elevated frontal view of a multi sheet unit fabricated in accordance with the disclosure of the invention. Figure 2 is a view taken along lines 2-2 of Figure 1. Figure 3 is an elevated frontal view of an assembly station incorporating features of the invention to align a side of a spacer frame in accordance with the disclosure of the invention. Figure 4 is a view taken along lines 4-4 of Figure 3 and having portions removed for purposes of clarity illustrating a side of the spacer frame out of alignment. Figure 5 is a view taken along lines 5-5 of Figure 3 and having portions removed for purposes of clarity illustrating the device of the invention to maintain the side of the spacer frame in alignment in accordance with the disclosure of the invention. Figure 6 is a cross sectional view of a side of a spacer frame modified in accordance with the disclosure of the invention. Figure 7 is an elevated top view of a horizontal assembly station incorporating features of the invention. Figure 8 is an elevated side view of a suction cup arrangement that may be used in the practice of the invention. Figure 9 is a view similar to the view of Figure 5 illustrating an alternate embodiment of a magnetic device of the instant invention to align a side of a spacer frame. SUMMARY OF THE INVENTION This invention relates to a method of manufacturing a multi sheet unit according to claim 1 that includes the step of maintaining in alignment a side (s) of a spacer frame secured to a sheet. According to the method of aligning a side of a spacer frame during fabrication of a multi sheet unit by mounting the spacer frame on a marginal edge portion of a major surface of a first sheet, wherein at least one side of the spacer frame is out of alignment, engaging at least one side of the spacer frame with a device and applying a force by way of the device to the at least one side of the spacer frame to move the at least one side of the spacer frame into alignment according to claim 1 this method is characterized by applying a magnetic or a negative pressure force to the at least one side out of alignment to move this side into alignment and positioning a sheet onto the spacer frame after the at least one side of the spacer frame is in alignment. As used herein and in the claims, a side of the spacer frame is that portion of the spacer frame between adjacent two corners of the frame. Further, as used herein and in the claims, a side of a spacer frame is in alignment when the surface of the sheet to which the spacer frame is attached lies in a plane that is generally perpendicular to a plane containing the outer surface of the base of the spacer frame. The multi sheet unit e. g. a double sheet glazing unit includes the spacer frame between and secured to each of the marginal edges of the sheets. The method includes, among other things, positioning the spacer frame on marginal edges of one of the sheets e.g. a first sheet on edge on a vertical position. The spacer frame is adhered to the first sheet by a layer of a sealant on outer surfaces of a leg of the spacer frame. After adhering the spacer frame to the first sheet, a side of the spacer frame may not be in alignment. The side of the spacer frame not in alignment due to slumping of the side when the glass sheets are assembled in the vertical position is due to gravity acting on the side of the spacer frame and/or stresses set up in the spacer frame during shaping of a flat metal strip into spacer stock and thereafter into the spacer frame. The bending of the sides of the spacer frame when the sheets are assembled in the horizontal position is due to the stresses set up in the spacer frame during fabrication as previously discussed. The side(s) of the spacer frame not in alignment is (are) moved into alignment and maintained in alignment by applying a force e.g. a magnetic field or vacuum to the side of the spacer frame out of alignment to maintain the side of the spacer frame in alignment. While the side of the spacer frame is in alignment, a sheet is positioned on a layer of sealant on the outer surface of the other leg of the spacer frame. The sheets are then biased toward one another to secure the sheets in position about the spacer frame and to seal the compartment between the sheets and within the perimeter of the spacer frame. Thereafter the applied force is removed. As can be appreciated, the applied force may be removed prior to the positioning of the sheet on the spacer frame, provided the side(s) of the spacer frame remain in alignment. The invention also relates to a work or assembly station according to claim 13 to practice the method. The station to assemble a pair of sheets of a multi sheet unit about a spacer frame comprises according to claim 13: a support for supporting at least one of the sheets, urging means selectively mounted on the support to move and maintain sides of the spacer frame out of alignment in alignment, being characterized in that the moving means is a magnetic means or a negative pressure applying facilities. The workstation includes facilities for supporting the first sheet having the spacer frame adhered thereto e.g. facilities for supporting the sheet on edge in a vertical position or in a horizontal position. Aligning facilities e.g. a magnetized rod or a vacuum cup is mounted on the supporting facilities to engage the side of the spacer frame out of alignment to align and/or maintain the side of the spacer frame in alignment. In the practice of the invention, the spacer frame is preferably made of metal e.g. stainless steel or galvanized iron responsive to magnetic forces; however, spacer frames made of non-metal or metal non-responsive to magnetic forces may have magnetically sensitive portions e.g. a metal disc adhered thereto in accordance with the practice of the invention. DESCRIPTION OF THE INVENTION With reference to Figs. 1 and 2 there is shown a multi sheet unit 10 fabricated in accordance with the teachings of the instant invention. The unit 10 includes a sheet 12 e.g. a first sheet joined to another sheet 14 e.g. a second sheet by an edge assembly 16 to provide a sealed compartment between the sheets. The edge assembly 16 includes a spacer frame 18 having in cross section as viewed in Fig. 2 a pair of outer legs 20 and 22 spaced from one another and joined by a base 24. The outer legs 20 and 22 may also be referred to as upright legs. This nomenclature is selected because the spacer frame when viewed in cross section is considered to have a "U" shape. For ease of discussion the "U" is considered upright regardless of whether it is upright or inverted as shown in Fig. 2. The outer legs 20 and 22 therefore for ease of discussion are considered upright regardless of whether they are upright or downward as shown in Fig. 2. A layer 26 of a moisture pervious adhesive material having a desiccant 28 is on inner surface 30 of base 32 of the spacer frame 18. A layer 34 of a moisture impervious sealant is provided on outer surface 36 of each of the outer legs 20 and 22. In certain instances, the spacer frame 18 is set in from the peripheral edges 38 of the sheets 12 and 14 to provide a peripheral channel 40 that is filled with a moisture impervious sealant 42. As can be appreciated, the invention is not limited to the material of the sheets which may be coated and/or uncoated sheets of glass, plastic and/or metal. Further the invention is not limited to the materials of sealants or the adhesive material and/or the material of the spacer frame. A more complete discussion of the unit 10 having the edge assembly 16 is disclosed in the EP Application which disclosure is hereby incorporated by reference. With reference to Fig. 3 the discussion will now be directed to vertical work or assembly station 50 incorporating features of the invention. The sheet 14 e.g. a first glass sheet was supported on one of the peripheral edges 38 in a generally vertical position and tilted toward backwall 52. The spacer frame 18 of the type previously discussed above and in the EP Application was adhered to marginal edge portions 54 of a major surface of the sheet 14 spaced inwardly from the peripheral edges of the sheet (see also Fig. 2). With continued reference to Figs. 3 and 4 the spacer frame 18 was maintained on the marginal edge portions 54 of a major surface of the first glass sheet 14 by the sealant layer 34 on outer surface 36 of the upright leg 22. The adhesive layer 26 having the desiccant 28 was mounted on the inner surface 30 of the base 32, and the sealant layer 34 was on outer surface 36 of the upright leg 20. As shown in Fig. 4, due to the weight of the spacer frame, sealant layer 34 on the upright leg 20 and the adhesive layer 26 having desiccant 28, upper side 56 of the spacer frame as shown in Fig. 3 tilts downwardly as shown in Fig. 4; more particularly, the side 56 was out of alignment as indicated by dotted lines 58 and 60. Mounted above the side 56 of the spacer frame 18 was a device 70 incorporating features of the inventions. With reference to Fig. 5, the device 70 included a horizontal leg 72 joined to leg member 74 by intermediate leg 76 to provide a generally "C" shape cross section, as viewed in Fig. 5. The member 74 had a cavity 78 in which was positioned a magnet 80. Mounted in the member 74 was a metal rod 82 having one end in the cavity in contact with the magnet 80 and extended downwardly as viewed in Fig. 5 away from the member 74. A resilient pad 75 was provided on the outer surface of the member 74 to prevent damage to the edge of the sheet. After the first sheet 14 having the spacer frame 18 was positioned on the backwall 52 of the workstation, the clamp 70 was positioned to set end 84 of the rod 82 in the plane having the base of the spacer frame when the side of the spacer frame is in alignment. Thereafter the side 56 of the spacer frame out of alignment was raised manually to engage the end 84 of the rod 82 as shown in Fig. 5, to maintain the side 56 of the spacer frame in alignment by magnetic forces. Thereafter, the sheet 12 is urged against the sealant layer 34 on outer surface 36 of the leg 20 of the spacer frame. The device 70 is then removed, and the sheets pressed together in a usual manner to flow the sealant layers and seal the compartment 17 between the sheets (see Fig. 2). As can be appreciated, the magnetic field may be increased to raise the side of the spacer frame out of alignment into alignment and maintain the side in alignment thereby eliminating the manually raising of the side. As used herein when the device 70 is maintaining the side of the spacer frame in alignment or the end 84 of the rod is in the plane of the base when the side of the spacer frame is aligned, the device is in the aligning position; when the device is not maintaining the side of the spacer frame in alignment or the end of the rod is not in the plane containing the base, the device is in the non-aligning position. As can be appreciated, the invention is not limited to the design of the holder for the magnet nor the force of the magnet. For example the clamp 70 is preferably made of aluminum; however, it may be made of any material e.g. plastic, stainless steel, wood. In regards to the force applied by the magnet, it should be sufficient to hold the side of the spacer frame in alignment. In the practice of the invention, a spacer frame having a thickness of 0.010 inch (0,254 mm), a base having a width of 21/32 inch (∼ 16,669 mm), the legs having a height of 0.300 inch (7,62 mm), a sealant layer having a thickness of 0.030-0.040 inch (0,762-1,016 mm) and an adhesive layer having a width of 21/32 (∼ 16,669 mm) and thickness of 0.080-0.100 inch (2,032-2.54 mm) having a desiccant and a length of about 2.1 meters required a force of 7 oz. (198 g) to maintain the side of the spacer frame in the line of alignment. The degree of slump, in other words, the intersection angle between the first plane and second plane measured 13°. A magnet having a force of 7 oz. (198 g) or greater was sufficient to hold the side of the spacer frame having the dimensions discussed above in the line of alignment. One technique to determine an acceptable force or number of magnets to hold the side of the spacer frame in alignment is to urge the base of the side of the spacer frame out of alignment against a magnet. If the side out of alignment is not held in alignment, there is insufficient force; the strength of the magnet should be increased or the number of magnets increased. The device may be mounted in the aligning position in any usual manner. For example and with reference to Figs. 3 and 5, a vertical plate 90 was mounted in the backwall. A magnet 92 was mounted on the intermediate leg 76 of the C clamp to secure the clamp to the vertical wall. With reference to Fig. 7 there is shown a horizontal assembly station. For horizontal assembly stations as well as vertical assembly stations, magnets may be provided at each side of the spacer frame as shown in Fig. 7. The practice of the invention is not limited to spacer frames made of metal e.g. stainless steel, galvanized iron. For example, but not limiting to the invention, if the spacer frame is made of a non-magnetic material e.g. aluminum or plastic, a magnetically sensitive disc e.g. disc 100 shown in Fig. 6 may be adhered to outer surface 102 of base 104 of the spacer frame 106 and/or the adhesive layer 26 may contain filings of a magnetically sensitive material. Further, the invention is not limited to a spacer frame having a "U" shaped cross section, e.g. the spacer frame may have box shaped cross section as shown in Fig. 6. Further, the spacer frame may have the base continuous around one or more corners or may have sections joined together as taught in the EP Application. Still further, the invention is not limited to the sealant adhering the spacer frame to the metal and any type of sealant may be used. With reference to Fig. 8, there is shown a vacuum device 120 that may be used to apply a force to the side of the spacer frame to maintain the side in alignment. The vacuum device 120 includes a vacuum cup 122 and a conduit 124 connected in any usual manner to a vacuum and/or pressure supply. In practice, a negative pressure may be pulled through the conduit 124 to maintain the side of the spacer frame in position. To release the vacuum cup, air under pressure may be moved through the conduit and/or the application of negative pressure may be terminated. Shown in Fig. 9 is another embodiment of the invention. The sheet 14 having the spacer frame 18 adhered to as previously discussed is supported on edge in the vertical position by the backwall 52. A device 130 incorporating features of the invention includes a flat member 132 having edge 134 supported on peripheral edge of the sheet 14. The member 132 is held in position by magnet 136 secured to undersurface 138 of the flat member 132 and adhered to the base 24 of the spacer frame 18 by magnetic force. The peripheral edge of the sheet 12 is moved under the device 132 in an upward direction as noted by arrowed line 140. The device 130 pivots in the direction of the arrowed line 142 to raise the device 132 and raise the side of the spacer frame into alignment. After the sheet 12 is in position e.g. adhered to the spacer frame by the layer 34 of the moisture impervious sealant, the device 130 is removed e.g. by lifting knob 144. As can now be appreciated, the embodiments of the invention discussed herein are not limiting to the invention and were presented for illustration purposes only. For example, in the instance where the sealant is a curable material, the sides of the spacer frame may be maintained in alignment practicing the invention while the material cures. Other embodiments as well as variations to the embodiments of the invention presented herein may be made within the scope of the invention as defined by the claims.

Claims: A method of aligning a side of a spacer frame (18) during fabrication of a multi sheet unit (10) by mounting the spacer frame (18) on marginal edge portion (54) of a major surface of a first sheet (12), wherein at least one side of the spacer frame (18) is out of alignment, engaging at least one side of the spacer frame (18) with a device and applying a force by way of the device to the at least one side of the spacer frame (18) to move the at least one side of the spacer frame (18) into alignment, characterized by applying a magnetic or a negative pressure force to the at least one side out of alignment to move this side into alignment and positioning a sheet (14) onto the spacer frame (18) after the at least one side of the spacer frame (18) is in alignment. The method of claim 1, characterized by the applying a force step to the at least one side is practiced by applying a vacuum to the at least one side. The method of claims 1 or 2, characterized by using a spacer frame (18) wherein the at least one side out of alignment is responsive to magnetic forces. The method of claim 3, characterized in that the spacer frame (18) is made of stainless steel. The method of claim 3, characterized in that the spacer frame (18) is made of a material that is non responsive to magnetic forces and the at least one side of the spacer frame (18) out of alignment is modified to be responsive to magnetic forces. The method of claim 5, characterized in that the at least one side of the spacer frame (18) out of alignment has a magnetic substrate applied thereto. The method of claim 5, characterized in that the at least one side of the spacer frame (18) out of alignment has a material adhered thereto that has metal filling mixed therewith. The method of any of claims 1 to 7, characterized by supporting the first sheet (12) in a vertical position by a vertical support surface and practicing the moving and urging at selected sides of the spacer frame (18). The method of any of claims 1 to 7, characterized by supporting the first sheet (12) in a horizontal position by a horizontal support surface and practicing the moving and urging at selected sides of the spacer frame (18). The method of any of claims 1 to 9, characterized by positioning the spacer frame (18) so that the base (24) is inset from the peripheral edges (38) of the first sheet (12) and after practicing the urging step flowing an adhesive (42) in the channel between outer surface of the base (24) of the spacer frame (18) and peripheral edges of the sheets. The method of any of claims 1 to 10, characterized in that the spacer frame (18) includes moisture pervious adhesive (26) having a desiccant therein on the inner surface (30) of the base (24). The method of any of claims 1 to 11, characterized in that the spacer frame (18) has four sides and the moving and urging steps are practiced at each side of the spacer frame (18). A station (50) to assemble a pair of sheets (12,14) of a multi sheet unit (10) about a spacer frame (18) comprising: a support (52) for supporting at least one of the sheets (12,14); urging means (70,120,130) selectively mounted on the support (52) to move and maintain sides of the spacer frame (18) out of alignment in alignment, characterized in that the moving means (70) is a magnetic means or a negative pressure applying facility. The station as set forth in claim 13 wherein the maintaining means (70,130) is a magnetic means. The station as set forth in claim 13 wherein the maintaining means (120) is a negative pressure applying facility. The station as set forth in one of claims 13 to 15 wherein the support (52) is in a generally horizontal plane. The station as set forth in one of claims 13 to 15 wherein the support (52) is mounted in a generally vertical plane. The station as set forth in claim 17 wherein a metal plate is mounted on the support (52) with the urging means (70,120,130) detachably secured on the metal plate. The station as set forth in claim 18 wherein the urging means (70) includes a C-shaped channel having a first leg (72), a second leg (74) and an interconnecting third leg (76), a first magnet (92) secured on the interconnecting leg (76) to secure the channel to the metal plate; a second magnet (80) on the first (72) or second leg (74), a rod (82) having a free end (84) and an opposite end connected to the second magnet (80) and a resilient pad (75) mounted on outer surface of the first (72) or second leg (74) having the magnet (80) to prevent damage to the edge of the glass by the channel.

Inventors: GALLAGHER RAYMOND G, KOVACIK PAUL J, ROSSKAMP BARENT A, THOMPSON ALBERT E JR, GALLAGHER, RAYMOND G., KOVACIK, PAUL J., ROSSKAMP, BARENT A., THOMPSON, ALBERT E., JR.
Applicants: PPG IND OHIO INC, PPG INDUSTRIES OHIO, INC.
Application year: 1996
Main classification: E06B3
IPC codes: E06B3, C03C27