Flexible or portable closure – partition – or panel – Framed type
Reexamination Certificate
1997-12-24
2001-08-28
Johnson, Blair M. (Department: 3634)
Flexible or portable closure, partition, or panel
Framed type
C160S378000, C160S383000
Reexamination Certificate
active
06279644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a screen and frame assembly for windows, doors and the like in which the screen is adhesively secured to the frame, and methods of manufacturing such products. In particular, this invention relates to screen and frame assemblies suitable for windows, doors, operable skylights and the like, for use in residential and commercial buildings.
2. Description of the Related Art
The general purpose of screens (also called “bug,” “fly,” or “insect” screens) is to eliminate the ingress of insects, while providing ventilation. A typical screen assembly is made up of screen cloth, fabric, or mesh attached to a screen frame in a manner discussed in more detail below. For brevity, the term “screen” will be used hereafter, and includes such screen cloth, fabric, mesh or similar ventilation material.
Screen frames for windows, doors, operable skylights and the like are commonly made of four elongated frame members, called screen bars, of uniform cross section. These bars are typically roll-formed from aluminum or sheet steel, although some may be extruded aluminum. (Plastic and wood are also used, but to a lesser extent.) These screen bars are supplied from the screen bar manufacturer in lineal form and are cut to a final length by the screen assembly manufacturer. Further, these screen bars are held together at the corners with plastic or metal inserts, called corner keys, to form the screen frame.
Different style corner keys are available and are designed to match the particular screen bar used. The most popular corner key allows the screen bar to be cut straight at 90° at the ends. These keys typically are made from injection molded plastic and have a square block body to visibly fill the corner area of the frame. Attached to the body are insertion prongs that are pushed into the hollow screen bar profile to create friction fit connections. Corner keys requiring a 45° miter cut on the ends of the screen bar also can be used. These keys, usually metal, are less expensive and entirely hidden inside the screen bar. These keys also provide a friction fit connection.
Screen is then affixed to the screen frame, in a manner discussed below, to form a screen and frame assembly. These assemblies are then removably secured to windows, doors (e.g., patio screen doors), operable skylights, and the like. Screen and frame assemblies for such openings are very similar, often differing only in size. Accordingly, for brevity, screen and frame assemblies for windows will be discussed hereafter. Nevertheless, it will be understood that this discussion applies equally to screen and frame assemblies for doors, operable skylights and the like.
The use of a removable screen and frame assembly in window openings facilitates cleaning of the window panes, as well as the screen itself. A removable assembly also facilitates the replacement of the screen in the event that it becomes torn or ripped. For these applications, the screen is light weight, and is, therefore, susceptible to being damaged by children, pets and household mishaps. Replacement also is necessary after the screen has excessively weathered. This can occur when the screen is exposed to extreme weather conditions for extended periods.
It is desirable that the screen be a light weight fabric or mesh, and stretched taut across the screen frame to avoid unsightly sag and to allow a viewer to see through the screen with minimal visual interference. However, if the screen is tensioned excessively, the screen bars will deform inwardly in an hourglass shape. This resultant shape not only is aesthetically undesirable, but also can prevent proper installation in the window opening. Excess screen tension also increases the risk of tearing the screen during manufacture of the screen and frame assembly or while the assembly is in service.
Typically, the screen is fiberglass yarn or roving, which is coated, for example, with polyvinyl chloride (PVC), woven and heat fused. The next most popular form of screen is made by weaving drawn aluminum wire, which is subsequently painted. The PVC coated fiberglass screen is the most popular type, by approximately a 4 to 1 ratio in area. However, both offer the desired attributes of suitable strength and an open weave.
To compensate for deformation of the screen frame into the hourglass shape discussed above, generally the screen bars are manufactured with an outward bow before the screen is installed. After the screen is installed, its final tension straightens the frame members in the final assembly. This “pre-bow” is set into the screen bar during the extrusion or roll-forming process to make the screen bar lineal.
Typically, roll-formed bar has approximately 20 millimeters (0.75 inches) of bow over a 3.7 meter (12 feet) length. Additional bow is usually set by hand into the roll-formed bar prior to screen installation when the length of the frame members is greater than 1 meter (approximately 3.5 feet). Pre-bowing is not required, however, when the screen bar is sufficiently rigid to resist deformation caused by the resultant screen tension.
It is the current practice, essentially industry-wide, to secure screen in open grooves formed along inside edges of the screen frames using a stuffer strip known as “spline” and its associated fastening techniques. The open grooves are known as “spline grooves.” Spline is often a wire-like, extruded rigid plastic or foam material, although some spline is made from metal, especially for use with aluminum screen. Spline is usually round or T-shaped in cross section, but can be U-shaped, for example.
U.S. Pat. No. 5,039,246 shows a conventional method of securing screen to a frame member using spline.
FIGS. 1A and 1B
of this application generally correspond to
FIGS. 3 and 2
, respectively, in that patent. Spline
58
is forced into spline groove or recess
56
in the screen bar
20
, with the screen
22
sandwiched between the spline
58
and the spline groove
56
. The screen
22
is held by friction between the spline
58
and the spline groove
56
with the resulting interference fit. A lip
50
and a ledge
52
, part way down one side of the groove wall, are typically included to help trap and improve the strength in retaining the screen
22
. The spline
58
and trapped screen
22
are forced into the groove
56
, usually by hand, with the use of a roller device
70
, including a roller
72
, as shown in FIG.
1
A. The term, “hand wiring”, is used to describe the action of securing the screen
22
with spline
58
into the spline groove
56
. Many attempts have been made to automate the installation of spline by machine. However, this automation has proven to be very difficult and machines of this nature have not been widely accepted as a viable option to hand wiring.
The conventional procedure for manufacturing and hand wiring a screen and frame assembly will be discussed in more detail below. First, the screen bars are cut to length, accounting for the corner key dimensions. Then, the screen frame is assembled using the cut screen bars and corner keys. As discussed above, when light construction screen bars are used, as is normally the case, a balance between pre-bow and screen tension is necessary to ensure straight screen bars and desirable tension in the final assembly. When the screen bar has insufficient pre-bow, the bars are deformed by hand a sufficient degree after the corner keys have been inserted. As discussed above, the amount of pre-bow is determined based on experience, but is typically a few millimeters of bow per meter length of the screen bar.
The screen frame is then secured to a table using locator (stop) blocks, which prevent shifting and maintain the frame square during screen installation. The table typically has permanent stop blocks for orienting the screen frame. To maintain the pre-bow, removable blocks are pushed against the center portions of the screen bars and then fastened to the table. (The spline groove must be facing up and unobstructed by the blocks.) More
Duane Morris & Heckscher LLP
Johnson Blair M.
St. Gobain Bayform America Inc.
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