HK1181438B - Grid runner - Google Patents

Abstract

A roll-formed grid runner comprising a sheet metal strip folded into an upper hollow single wall reinforcing bulb, a double wall web below the bulb, a channel extending laterally from both sides of a lower end of the web to a bend and upwardly from the bend to a panel supporting elevation, the bend on each side of the web existing at a longitudinally extending score line where a thickness of the strip is locally reduced.

Description

Grid keel

Background

The present invention relates to suspended ceiling grid runners, and in particular to roll formed sheet metal grid runners having novel cross sections.

Prior Art

In addition to generic inverted T-shaped profiles, different grid runner profiles have been proposed to achieve a variety of ceiling visual effects, appearances, and functions. Such a grid runner disclosed in U.S. patent No. 4,794,745 has a centrally located box-like cross-section below the flange elements of a plurality of opposed support panels. Manufacturing such prior art profiles from a single strip may necessarily require expensive roll-forming tools and the resulting product is asymmetrical about a vertical centerline. From a practical standpoint, this prior art single strip construction may require that its entirety be coated, including its non-visible portions, which typically comprise a large portion of the coated side of the entire strip. Furthermore, roll-forming equipment producing such prior art shapes may be difficult to maintain to achieve consistent results.

Summary of The Invention

The present invention provides a unique grid runner profile having a central channel structure beneath opposed panel-supporting flange elements. The disclosed profile may be generally symmetrical and can be manufactured with relatively simple tools. The present invention differs from conventional roll-forming techniques in that the profile is formed without a support roll on the inside corner of the channel structure that hangs below the flange elements of the support panels.

In the preferred embodiments disclosed, the suspended channel and flange element are capped in a conventional manner with a veneer or tape. Only this facing strip needs to be coated as it is the only visible portion of the novel grid tee after installation of the panels of the ceiling tiles.

Brief description of the drawings

FIG. 1 is an isometric fragmentary view of a grid runner embodying the present invention shown with respect to a typical slot-engaging ceiling panel; FIG. 2 is a cross-sectional view of the grid runner of the present invention; figure 3 is a greatly enlarged scale fragmentary cross-sectional view of the sheet metal strip to be rolled into the grid runner body of figures 1 and 2, showing one score line for use with the present invention; FIG. 4 is a fragmentary cross-sectional view on an enlarged scale of a fold area of the grid runner of FIGS. 1 and 2 made on the score line of FIG. 3; fig. 5A-5M are diagrammatic representations of sequential rollers of a primary roll assembly used to produce the grid runners of the present invention; and is

Fig. 6A-6L are diagrammatic representations of sequential rollers of a secondary roll assembly used to produce the grid runners of the present invention.

Description of the preferred embodiments

Referring now to the drawings and in particular to fig. 1 and 2, there is shown a short length of an elongated grid runner or tee 10 made in accordance with the present invention. The tees 10 are used to construct a rectangular grid for a suspended ceiling in a generally conventional manner. Such tees 10 may be used for main tees and cross tees, as is known in the art. Conventional end connector elements (either integrally stamped or attached clips) are provided on both ends of the tee 10, and a plurality of perforations for suspension wires and a plurality of slots for cross tee end connectors are stamped along the body of the tee, as in the manufacturing method referenced below. The tee 10 comprises two separate sheet metal strips 12, 13 which are roll formed into the cross-sectional shape shown in fig. 1 and 2. A rectangular grid of major and minor tees 10 can support conventional rectangular ceiling panels or tiles 14, which in the example illustrated in fig. 1 are notched at their edges so that the visible portions of the tees are recessed into the plane of the tiles.

The cross-section of the tee 10 includes an upper hollow generally rectangular reinforcing or reinforcing bulb 16, a vertical web 17 depending from the bulb, a lower U-shaped channel 18 bisected by the web, and oppositely extending horizontal panel-supporting flanges 19 at the upper edge of the channel.

Preferably, the elements of the tee section are symmetrical about a central vertical plane. Describing the tee 10 in more detail, the body strip 12 is folded by one of the roll forming methods discussed below into an upper reinforcing bulb 16 having a single layer wall. The body strip 12 is folded so that it converges at the mid-plane of the tee 10 to form the web 17 as a double layer. At the bottom of the web 17, portions of the body strip 12 are folded so that they diverge generally horizontally to form an inner layer of the bottom 23 of the channel 18. At an area spaced from the web 17, the body strip 12 is folded or bent generally vertically upwardly to form inner portions of both sides 22 of the channel 18. At the upper region of the channel 18, the body strip 12 is folded horizontally outwardly to form an upper layer of flanges 19.

The bottom 23 and sides 22 of the channel 18 and the flange 19 are covered by the facing strip 13. The facing strip 13 is locked to the body strip 12 by a plurality of flaps 24 made by folding the edge region of the facing strip around the longitudinal edge 26 of the main or body strip 12 at the distal edge of the flange 19. When the ceiling panels 14 are installed on the grid of tees 10, only the veneer or cover strip 13 is visible so there is no need to coat the body panels. The veneer or strip 13 is coated or otherwise provided with a desired decorative coating or finish. Typically, the body strip 12 and the facing strip 13 are formed of steel, although other metals may be used for one or both of the strips. For example, the body sheet may be a galvanized 0.016 inch gauge steel sheet for a main tee and 0.014 inch gauge steel sheet for a cross tee. The veneer 13 may be a lighter gauge, such as 0.0085 inch.

The proximity of the vertical sides 22 of the channels 18 to the web 17 and the presence of the reinforcing bulbs 16, which are located above the space between the web and the channel sides, make conventional techniques impractical for roll forming the cross-sectional shape of the tee 10. In forming the corners between the bottom 23 of the channel 18 and each side 22 thereof, there is not enough space for forming rolls of sufficient strength to support the metal blank on the sides of the body strip 12. The presence of the connector at the end of the tee 10 exacerbates the problem of insufficient clearance. The present invention overcomes this problem by eliminating the need for multiple support rollers in this area. The method of the present invention involves pre-adjusting the body strip 12 in the areas that ultimately become the corner locations of these channels. This pre-adjustment step is achieved by: the body strip 12 is weakened by scoring it along longitudinal lines that are positioned where the channel corners are desired in the finished product. The following disclosure presents a preferred mode of carrying out the method of the present invention.

A grid T-shaped preform 31 (fig. 5M) is manufactured in a primary roll assembly depicted in fig. 5A-5M. The grid tee stock exiting the primary roll assembly is rough cut to length and positioned in a press to cut it to precise length, suspension wire penetrations and cross tee slots are formed therein, and an integral end connector pattern is stamped or separate end connectors are attached as is customary in the industry. After the stamping operation is performed, the T-shaped preform 31 is passed through a secondary rolling assembly depicted in fig. 6A to 6L to finally shape it.

In fig. 5A-5M and 6A-6L, only a portion of each roll station is shown, it being understood that each roller in a station is symmetrical about the mid-plane of the tee. Describing the operation of the primary roll assembly (fig. 5A-5M) in more detail, a flat body strip 12 (typically fed from a roll of material) is passed between the rollers of the first station shown in fig. 5A. Carbide roller segments 36 near the outer end of a top roller unit each have a small circumferential rib positioned on the circumferential line indicated at 37, radially away from the circular area around the roller, for example 0.008 inches. The rib 37 located in the center of the axial length of the carbide roller section 36 has substantially the same profile as the groove or score 38 shown in fig. 3, which is permanently formed in the body panel 12. By way of example, score 38 may be about 0.006 inches to about 0.008 inches deep. The part of the body plate shown in fig. 3 is on a greatly enlarged scale. Although, as mentioned, only a portion of each roll stand is shown, ribs 37 are present on the carbide roll segments 36 adjacent both lateral boundaries or edges of the body strip 12 such that two parallel longitudinally extending score lines 38 are formed in these boundary regions of the strip.

Fig. 5B-5K diagrammatically show sequential roll stations with top and bottom roll assemblies that progressively roll form the body strip 12 into a tee shape in a generally conventional manner, although the tee shape is somewhat higher than a standard profile. At the roll stand of fig. 5L, the facing strip 13 is introduced onto the bottom flange regions of the body strip 12. Fig. 5M illustrates the grabbing or final assembly of the finish strip 13 onto the body strip 12, with the roll set folding the border region of the finish strip back over the longitudinal edges 26 of the body strip 12 to form the flaps 24 (fig. 2 and 4).

Preferably, the layers of the web 17 are locked together with a plurality of stitches 39 before cutting the preform 31 to length and typically before the last roll station of the primary roll assembly (fig. 5M). This is done, for example, by a known method (such as that disclosed in U.S. Pat. No. 6,047,511) which can be modified as follows: rather than (as shown in the patent) first compressing the material slit from the web 17 to cause it to expand relative to the slit perforation from which it was cut, the material is first compressed around the slit perforation to cause the perforation to contract relative to the material slit from the perforation. As shown in fig. 1, two vertically spaced rows of stitching 39 may be formed in the web 17. These stitching 39 improve the stability of the grid T-shaped preform 31 as it passes through the secondary roll set.

As previously mentioned, the preformed tee 31 made of the combined body strip 12 and face strip 13 completed in the primary roll assembly of fig. 5A-5M is rough cut to length and passed through a punch. After the preform tee 31 is processed in the press, it is passed through a secondary roll assembly shown schematically in fig. 6A-6L. Each drawing proceeding from fig. 6A to 6L represents a sequential rolling assembly. Inspection of these roll assembly views shows that there is no upper roller support on the upper side of the preformed flange (indicated at 40 in fig. 6A, vertically below bulb 16). A closer examination of fig. 6B-6L reveals that the preformed flange 40 is bent upwards at the score lines 38 on each side of the web 17, although there is no support roll inside the score lines 38 on the upper side of the flange 40 in each of the illustrated stations. This bending is initiated in the roll station shown in fig. 6B where the lower roller 46 deflects the flange 40 upwards. The rollers in the stations shown in fig. 6B to 6K progressively deform each side of the flange 40 through a series of gull-wing stages. The station of fig. 6K angles the gull-wing feature of the tee flange off the station shown in fig. 6J. The tee 10 is final formed in the station of fig. 6L. Throughout the stations, 6B to 6L, the score lines 38 (like creases in a piece of cardboard) locally locate the fold of the flange 40, even if there is no support roller inside this fold.

It should be understood that the present disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. Therefore, the invention is not to be limited to the specific details of the disclosure except to the extent that the following claims are necessarily limited.

Claims (4)

1. A grid runner roll-formed from sheet metal comprising a main body sheet and a face sheet, the main body sheet having a cross-section including an upper hollow reinforcing bulb, a vertical double wall web extending downwardly from the bulb, a channel extending laterally at the bottom of the web from both sides of the web to a bend and upwardly from the bend to the level of a support panel to form a panel-supporting flange extending laterally outwardly to an edge, and a facing sheet wrapped around the outer surface of the channel and the lower surface of the flanges and returned around the edges of the flanges and on the upper surface at the boundary of the flanges adjacent said edge, the horizontal width of the channel at the bends being less than the width of the reinforcing bulb.

2. A grid runner as set forth in claim 1, wherein the main body plate is scored at the bends.

3. A grid runner as set forth in claim 2, wherein the scores are located at an inner surface of the channel.

4. A grid runner as set forth in claim 1, wherein the facing sheet has a convex shape between the bends such that it is vertically spaced from the main body sheet in the area between the bends.