SPACER BAR HAVING INTERLOCKING SEAM FOR USE IN MULTIPANE WINDOWS AND METHOD OF MAKING SAME

Abstract: A tubular spacer bar (16, 48) for use in the construction of hermetically sealed multipane windows is formed of a metal strip having a first edge portion (18, 50) and a second edge portion (19, 70) that are brought together to form a seam. In one embodiment of the spacer bar (16), the first edge portion (18) is formed into a series of adjacent tabs (20, 22, 24, 26, 28) that are alternately bent in opposing directions to overlie and underlie alternately the second uncut, untabbed edge portion (19). The tabs (20, 22, 24, 26, 28) are then compressed against the untabbed second edge portion (19) to form an interference lock between alternate tabs in a direction along the spacer bar seam, thereby preventing movement of the edge portions relative to one another in a direction along the seam. In a second embodiment, both the first edge portion (50) and second edge portion (70) are formed into a series of tabs (52, 54, 56, 58, 72, 74, 76, 78) and the tabs are brought together in interleaved fashion in alternate overlying and underlying arrangement such that the tabs from opposing edge portions directly adjacent one another in a direction along the seam after the tabs are compressed against one another. The adjacent arrangement of tabs from opposing edge portions prevents movement of the edge portions with respect to one another in a direction along the seam, thereby providing rigidity and twist-resistance to the spacer bar (48).

Description: SPACER BAR HAVING INTERLOCKING SEMI FOR USE IN MULTIPANE WINDOWS AND METHOD OF MAKING SAME". Background of the Invention This invention relates to components for use in multipane insulated window construction and more particularly relates to a spacer bar having an interlocking seam. This is a continuation-in-part of my copending application Serial No. 333,290, filed December 22, 1981. In the construction of insulated windows having multiple panes of glass, it is necessary to provide a spacer frame between adjacent panes to maintain the separation of the panes. Typically, the spacer frames are constructed of sections of spacer bars joined at the corners to form a closed frame. The spacer bars are generally hollow and filled with a dessicant to absorb moisture from the air trapped between the panes to prevent fogging of the panes. If the dessicant is to perform its moisture-absorbing function, there must be an airflow into and out of the interior of the spacer bar so that the moist air can contact the dessicant. It is therefore necessary that the spacer bars contain openings to accommodate this airflow. The usual and most economically efficient spacer bar construction is by forming the bars from sheet metal. In such spacer bars, the openings for air flow to the interior of the bar are provided either as a part of or adjacent the seam of the spacer bar. It is, however, necessary to ensure that the openings for airflow are not large enough to permit any dessicant to leak from within the spacer bar even if a powdered dessicant is used. In constructing insulated window units of large size, for example, four to eight feet on a side, long lengths of spacer bar are necessary. Such long lengths of spacer bar formed in accordance with the prior art methods are subject to twisting and can twist under the force of the sealant that is injected along the edge of the window to seal the panes to the spacer bar. When such twisting occurs, it is then necessary for an operator to manually attempt to straighten the spacer bar prior to continuing construction, thereby consuming time and increasing the labor costs involved in window construction. The major cause of the lack of resistance to twisting of long lengths of spacer bar made in accordance with the prior " art methods is in the ability of the abutting edges of the spacer bar along each side of the seam to slide longitudinally with respect to one another. Attempts have been made to add rigidity to the spacer bars by welding the seams to provide strength, however, most welding operations require the infusion of large amounts of new capital to the production facilities and greatly decrease the profitability of the manufacturing operation. Further, if a continuous weld is utilized, an additional step of perforation must be performed to provide the necessary openings along the seam for air to flow in and out of the interior of the spacer bar containing dessicant. Summary of the Invention The present invention provides a spacer bar for use in a hermetically sealed multipane window that has a seam that resists movement of the opposing edge portions of the seam with respect to one another in a direction along the seam. The spacer bar is formed from a strip of metal having a first edge portion and a second edge portion. In a first embodiment of the seam of the present invention, a series of lateral cuts is made to form a series of tabs along the first edge portion. Alternate ones of the tabs are bent in a first direction out of the plane of the metal strip a distance approximately equal to the thickness of the metaL The strip is then formed by conventional processes to the shape of a tubular spacer bar and the uncut second edge portion is brought into juxtaposition with the tabbed first portion so that the second portion is interleaved between the tabs with the tabs alternately overlying and underlying the second edge portion. Pressure is then applied from within' and without the spacer bar along the seam to compress the tabs against the uncut second edge portion of the spacer bar to lock the joint against separation. The spacer bar formed in accordance with the above method has a first edge portion and a second edge portion, the first edge portion being formed into tabs with alternate ones of the tabs overlying the second edge portion. Preferably, one surface, for example, the inner surface, of the spacer bar along the seam is held flat while pressure is applied along the seam against a second surface, for example, the outer surface, with a grooved instrument so that the finished spacer bar has, for example, the inner surface substantially flat, while the outer surface protrudes along the seam. The interference between adjacent tabs in a direction along the seam prevents relative movement between the first OMPI edge portion and the second edge portion of the spacer bar in a direction along the seam, thereby providing rigidity to the spacer bar. In a second embodiment of the seam of the present invention tabs are formed in both the first and second edges of a strip of sheet metal. The tabs on the first edge are substantially in line with the tabs on the second edge. Alternate ones of the tabs on the first edge are bent in a first direction out of the plane of the strip a distance approximately equal to the thickness of the metal. The tabs on the second edge that are in line opposite the unbent tabs of the first edge are bent out of the plane of the strip in the first direction also a distance approximately equal to the thickness of the metal. The sheet metal strip is then formed by conventional processes into a tubular spacer bar bringing the first edge and the second edge of the sheet metal strip into juxtaposition so that the bent tabs on the first edge of the strip overlie the unbent tabs on the second edge of the strip. At the same time, the bent tabs on the second edge of the strip will overlie the unbent tabs on the first edge. The seam of the spacer bar at that time comprises a series of interleaved tabs. Pressure is then applied on the seam from within and without the tubular spacer bar by rollers and dies in a conventional manner to compress the interleaved tabs against one another and lock the joint against separation. The spacer bar formed in accordance with the above method has a first and second edge portion, both edge portions being formed into tabs that are essentially in line with one another. Alternate ones of the tabs of the first edge overlie their counterpart tabs of the second edge and the remaining tabs of the second edge overlie their counterpart tabs of the first edge, such that in a direction along the seam, alternate tabs from the first edge are side-by-side with alternate tabs from the second edge. The side-by-side relation of alternate tabs from each edge causes the tabs to interfere with one another in a direction along the seam, thereby preventing movement of the first edge relative to the second edge in a direction along the seam, lending rigidity to the spacer bar. Brief Description of the Drawings The above-stated features and advantages of the present invention will be best understood by those of ordinary skill in the art and others upon reading the ensuing specification when taken in conjunction with the appended drawings wherein: FIGURE 1 is an exploded isometric view of a multipane insulated window construction; FIGURE 2 is an isometric view of one embodiment of a spacer bar f OOMMPPII (fyy_ WIPO made in accordance with the principles of the present invention prior to final formation of the seam; FIGURE 3 is an isometric view of the spacer bar of FIGURE 2 after final seam construction; FIGURE 4 is an end view of the spacer bar shown in FIGURE 3 during final seam construction; FIGURE 5 is an isometric view of a second embodiment of a spacer bar made in accordance with the principles of the present invention prior to final formation of the seam; FIGURE 6 is an isometric view of the spacer bar of FIGURE 5 after final seam construction; and FIGURE 7 is an end view of the spacer bar of FIGURE 6 during final seam construction. Detailed Description of the Preferred Embodiment Referring now to FIGURE 1, a multiple pane insulated window typically consists of two or more panes 10a, 10b, and 10c of glass, plastic, or other transparent material separated by a frame comprised of tubular spacer bars 12a, 12b, 14a, and 14b. Adjacent ends of the spacer bars are typically joined together to form a continuous frame, which is interposed between the panes 10a, 10b, and 10c of the window. The tubular spacer bars of each frame can be joined by means of cornerpieces (not shown) inserted into the adjacent ends of the spacer bars. The window shown in FIGURE 1 consists of three panes of glass separated by two sets of spacer bars, however, the window construction would be nearly identical if only two panes of glass or more than three were used, although typically a window will have only two or three panes. Once the panes and spacer frames are positioned in proximity to one another, a thermoplastic adhesive or other suitable material is injected around the edges of the glass and spacer bars sealing the panes of glass and spacer bars into a single unitary window assembly (not shown). Typically, each of the tubular spacer bars 12a, 12b, 14a, and 14b is filled with a dessicant, for example, silica ge The dessicant's moisture- absorbing properties draw moisture from the air trapped within the space between the adjacent window panes 10a and 10b or 10b and 10c bounded by the tubular spacer frame, thereby preventing moisture from collecting on the interior portions of the window panes and fogging the window. Referring now to FIGURE 2, a portion of one embodiment of a typical spacer bar 16 is shown prior to forming of the seam. The spacer bar 16 is formed of a single strip of metal bent into tubular form and having a seam formed in accordance with the present invention. The general shape of the spacer bar, apart from the seam, is conventional, and the seam of the present invention is useful with other shapes of spacer bar as well. In the formation of the seam, a first edge portion 18 of the metal strip used to form the spacer bar 16 is cut in a straight line. A second opposing edge portion 19 of the metal strip, which will form the other half of the seam, has a series of lateral slits therein to form a series of tabs 20, 22, 24, 26 and 28 (only a portion of which is shown). A separation is formed between adjacent tabs 20 and 22, 22 and 24, 24 and 26, and 26 and 28 of a size sufficient that the first edge portion 18 of the strip can be fitted in an interwoven fashion between adjacent ones of the tabs so that the tabs alternately overlie and underlie the first edge portion 18. The separation between the tabs 20 through 28 can be accomplished by bending every other tab, for example, 20, 24, and 28 in a first direction out of the plane of the sheet metal strip and leaving the remaining tabs 22, 26 in their original plane. Alternatively, the tabs 20, 24, and 28 can be bent in a first direction out of the original plane and the tabs 22 and 26 can be bent in a second, opposite direction out of the plane in order to provide sufficient spacing for the edge portion 18 to be fitted between adjacent tabs. Typically, the formation of the tabs 20 through 28 and the bending of the tabs is performed prior to the formation of the metal strip into tubular shape, however, the operation can be performed at any point prior to final joining of the seam, depending on the particular tooling used to perform the operation. Once the basic tubular shape has been achieved, the seam is closed by bringing the first edge portion 18 and the second edge portion 19 into overlapping relationship. The first edge portion 18 is interwoven in over-and- under pattern with the respective tabs 20 through 28, and the distal surface of the first edge portion 18 abuts the edge portion 19 at the location of the attachment of tabs 20 through 28 to the remaining portion of the sheet metal strip. Once the seam has been closed, the tabs are compressed against the straight edge 18 in order to lock the seam so that the spacer bar seam will remain closed after the bar has been removed from tooling and is utilized in construction of windows. FIGURE 3 illustrates the completed spacer bar 16. Referring now to FIGURE 4, compression of the seam is typically accomplished by passing a roller 30 along the length of the seam exerting a force in a downward direction on the spacer bar seam as viewed in FIGURE 4. A die 32 is located on the interior of the spacer bar and has a shape congruent to the shape of the spacer bar. An upper surface 34 of the die 32 is flat and counteracts the downward force exerted by the roller 30, thereby squeezing the " OMPI tabs against the interwoven first edge portion 18 to lock the seam. The roller 30 has a notch 31 formed therein to accept the thickness of the seam caused by the overlap of the two edge portions 18 and 19. Since the roller 30 is notched and the upper surface 34 of the die is flat, the final seam will be flat along the interior of the spacer bar and will protrude outwardly along the seam exterior to the spacer bar. The lower tabs 22 and 26 during the compression process will be forced upwardly, stretching the metal of the first edge portion 18 which overlies the tabs 22 and 26, and forming slight humps 36 and 38 in the seam as shown in FIGURE 3. The lines 40 are an attempt to illustrate the stretching of the metal along the edge portion 18 overlying the tabs 22 and 26. The spacer bar 16 with the joint formed in accordance with the invention as described and illustrated, is much more rigid and resists twisting more effectively than spacer bars formed by prior art methods. The resistance to twisting is due to the inability of the edge portions 18 and 19 to move longitudinally with respect to one another, that is, in a direction along the seam once the seam has been formed. The humps 36 and 38 formed in the final seam lie between tab pairs 20 and 24, and 24 and 28, respectively. The humps thereby interfere with and prevent the movement in a direction along the seam of the tabs 20, 24, and 28 locking the edge portions 18 and 19 in a direction along the seam. Prevention of the sliding of the joints also prevents consequent twisting of the spacer bar. While the joint formed in accordance with the present invention provides rigidity to the bar, it still allows a flow of air through the joint since the joint is not airtight to the interior of the spacer bar, thereby permitting dessicant within the spacer bar to absorb moisture from the space between adjacent panes of glass. If desired, a knurling wheel can be run along the length of the seam to further form the metal and add further strength to the, seam. Whether the protruding side of the seam is on the exterior or interior of the spacer bar is determined by the roller and die combination used in the final formation process and does not affect the function or operability of the seam of the present invention. For example, if the roller 30 did not contain notch 31, but rather was flat across its outer circumference, and instead a notch was formed in the upper surface 34 of the die 32, the resulting seam would be flat along the exterior of the spacer bar where it was rolled by the roller and the protrusion of the seam would occur in the interior of the spacer bar where the notch was formed in the die. In that event, only the appearance of the bar would be altered. Functionally, the bar would remain the same. Referring now to FIGURE 5, a portion of a second embodiment of a spacer bar 48 made in accordance with the principles of the present invention is illustrated prior to final formation of the seam. In this second illustrated embodiment, a first edge portion 50 of the sheet metal piece utilized to form the spacer bar 48 is formed into a series of tabs 52, 54, 56 and 58. A vertical space, as viewed in FIGURE 5, approximately equal to the thickness of the sheet metal is formed between adjacent ones of the tabs by bending alternate ones of the tabs, that is, 52 and 56 in a first direction out of the plane of the sheet metal and leaving the remaining tabs 54 and 58 in the plane of the sheet metal or by bending the tabs 54 and 58 in a second, opposite direction. Up to this point, the construction of the second embodiment coincides with construction of the first embodiment of the spacer bar discussed above. In the embodiment pictured in FIGURE 5, a second edge portion 70 of the sheet metal piece is also formed into a series of tabs 72, 74, 76 and 78. Alternate ones of the tabs 72 through 78 are bent upwardly in a first direction out of the plane of the sheet metal a distance substantially equal to the thickness of the metal. However, the tabs 74 and 78 that are bent upwardly along the second edge portion are the tabs that lie opposite the tabs 54 and 58 of the first edge portion across the seam, while tabs 72 and 76, which are opposite tabs 52 and 56, are bent slightly downwardly. Therefore, when the- edge portions 50 and 70 are brought into juxtaposition, overlapping one another, the tab pairs across the seam, 52 and 72, 54 and 74, 56 and 76, and 58 and 78, alternately underlie and overlie one another to form an interleaved tabbed seam. The seam is then compressed, again using rollers and dies as described above and illustrated in FIGURE 7 to form the final seam configuration. A die 80 of a shape congruent to the shape of the spacer bar lies within the spacer bar. The die 80 has a flat surface 82 adjacent the seam. A roller 84 overlies the seam and applies a downward force against the seam compressing the tabs of the seam between the roller 84 and the die 80. The roller 84 has a notch 86 formed in its surface to accommodate the thickness of the seam. The seam therefore protrudes along the of the spacer bar. As can be seen in the illustrations, after compression of the seam, tabs from opposing sides of the seam lie in substantially the same plane adjacent one another in the final configuration. For example, tabs 52, 74, 56 and 78 substantially lie in a first plane, while tabs 72, 54, 76 and 58 lie substantially in a second plane subjacent the first plane. The interference between the adjacent tabs prevents movement of edge portion 50 and 70 with respect to one another in a direction along the seam, again providing rigidity to the seam which resists twisting of the spacer bar during the window construction process. In FIGURE 7, the surface of the notched portion 86 of the roller 84 has a series of knurling ridges 88 formed across the notch. The ridges 88 form grooves 90 along the seam, lateraEy oriented to the longitudinal dimension of the spacer bar. The action of the knurled roller 84 in forming the grooves 90 also deforms the tabs slightly into a wave pattern. While the seam formed by a flat surfaced roller provides sufficient clearance in the seam for air to flow in and out of the spacer bar, i.e., allows the spacer bar to "breathe," the "breathing" of the bar is enhanced by the use of the knurled roller 84. While preferred embodiments of the present invention have been described and illustrated, it will be understood by those of ordinary skill in the art and others that certain modifications can be made to the illustrated embodiments while remaining within the scope of the present invention. For example, as discussed, the protrusion of the seam can be made to occur either on the exterior of the spacer bar or the interior of the spacer bar without affecting the functionality of the seam. Also, while rectangular tabs are illustrated, the tabs could be of other shapes, as long as their formation causes interference in a longitudinal direction along the seam. Therefore, the invention should be defined solely with reference to the appended claims.

Claims: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1. A method of forming a strip of metal having first and second edge portions into a tubular spacer bar for a multipane window comprising the steps of: a) making a series of lateral cuts in said first edge portion of said strip to form said first edge portion into a series of adjacent tabs; b) bending alternate ones of said tabs out of the plane of said strip in a first direction a distance approximately equal to the metal thickness; c) bending parts of said strips between said edge portions thereof to form a tubular spacer bar and to bring said edge portions into overlapping relationship with each other in such a manner that said second edge portion of said strip is disposed within the space between said bent tabs and said straight tabs in interwoven fashion, said tabs alternately overlying and underlying said second edge portion; d) supporting the inner surface of said spacer bar along said overlapped edge portions by means of a die disposed within the spacer bar while passing a roller over the exterior of said spacer bar to exert roll pressure on the outer surface of said spacer bar adjacent said edge portions to compress said tabs against said second edge portion of said strip. 2. The method of Claim 1 further including the step, after bending said alternate tabs in said first direction, of bending the remaining tabs in a second direction out of the original plane of said metal strip prior to bringing said first and second edge portions of said strip into overlapping relationship. 3. The method of Claim 1 wherein said die has a flat surface adjacent said edge portions and wherein said roller has a notch formed therein that overlies said edge portions. 4. The method of Claim 1 wherein said roller has a flat surface overlying said edge portions and wherein said die has a notch in register with said edge portions. 5. The method of Claim 3 wherein the surface of said roller that contacts said tabs is knurled. 6. A method of forming a strip of metal having first and second edge portions into a tubular spacer bar for a multipane window comprising the steps of: a) making a series of lateral cuts in said first edge portion of said strip to form a series of adjacent said first edge portion; b) making a series of lateral cuts in said second edge portion of said strip to form a series of adjacent tabs along said second edge portion; e) bending alternate ones of said tabs of said first portion out of the plane of said strip in a first direction a distance at least equal to the metal thickness; d) bending alternate ones of said tabs of said second edge portion out of the plane of said strip in said direction a distance at least equal to the metal thickness; e) bending parts of the strip between said edge portions thereof to form a tubular spacer and to bring said edge portions into overlapping relationship in such manner that said bent tabs of said first edge portion overlie said unbent tabs of said second edge portion and said bent tabs of said second edge portion overlie said unbent tabs of said first edge portion; f) supporting the inner surface of said spacer bar along said overlapped edge portions by a die disposed within said spacer bar while passing a roller over the outer surface of said spacer bar along said overlapped edge portions to exert roll pressure on said overlapped edge portions to compress said tabs of said first and second edge portions against one another. 7. The method of Claim 6 wherein said die has a flat surface adjacent said edge portions and said roller has a notch formed therein that overlies said edge portions. 8. An elongate tubular spacer bar for use in a hermetically sealed multipane window formed from a metal strip, said spacer bar having a nonwelded seam running along the elongate dimension of said spacer bar between edge portions of said strip, said nonwelded seam being formed such that the edge portions of said strip are substantially immovable relative to one another in a direction along the elongate dimension of said strip. 9. The spacer bar of Claim 8 wherein one edge portion of said strip is formed in a series of tabs alternately overlying and underlying a second edge portion of said strip. 10. The spacer bar of Claim 9 wherein said first and second edge portions are locked against movement with respect to one another in a direction along said seam by means of an interference between said tabs of said first edge and the metal of said second edge that has been deformed so as to lie between alternate ones of said tabs of said first edge. . 11. The spacer bar of Claim 8 wherein said first edge portion of said strip is formed in a series of tabs and said second edge portion of said strip is formed in a series of tabs, said opposing tabs of said first and second edge portions alternately overlying and underlying one another in an interleaved fashion such that the tabs of said first edge and second edge are adjacent one another and lie in the same plane to interfere with movement of said edge portions relative to one another along the elongate dimension of said spacer bar, thereby forming a locked seam.

Inventors: PETERSON WALLACE HARVEY, PETERSON, WALLACE, HARVEY
Applicants: PETERSON METAL PROD, PETERSON METAL PRODUCTS LTD.
Application year: 1982
Main classification: B21D39
IPC codes: B21C37, B21D53, B23P11, E06B3