US3378976A

US3378976A - Ceiling framework

Info

Publication number: US3378976A
Application number: US486093A
Authority: US
Inventors: Jr Thomas C Meredith
Original assignee: R B M METALS Co Inc
Current assignee: R B M METALS Co Inc; Rbm Metals Company Inc
Priority date: 1965-09-09
Filing date: 1965-09-09
Publication date: 1968-04-23
Anticipated expiration: 1985-04-23

Description

April 1963 T. c. MEREDITH, JR 3,378,976

CEILING FRAMEWORK Filed Sept. 9, 1965 OMAS C. MEREDITH JR. FIG 2 BY M, @m, mkmf fifg ATTORNEYS United States Patent 3,378,976 CEILING FRAMEWORK Thomas C. Meredith, Jr., Columbia, S.C., assignor to R.B.M. Metals Company, Inc., Columbia, S.C., a corporation of South Carolina Filed Sept. 9, 1965, Ser. No. 486,093 12 Claims. (Cl. 52--573) ABSTRACT OF THE DISCLOSURE A ceiling suspension grid in which a snap fit is obtained between a notched groove on the tongues of the cross frame members and a tab in the aperture of the upright portion of the main frame members.

This invention relates to a framework for a suspended ceiling and more particularly to a fire-rated ceiling framework which may withstand extreme heat from a fire.

False ceilings are often constructed by supporting a plurality of fireproof ceiling panels on an overhead ceiling framework which is in turn suspended in spaced-apart relation from a main ceiling in order to provide a space for lighting fixtures, air conditioning, or the like. The false ceiling surface formed by the plurality 'of fireproof panels is intended to serve as a fire wall in order to prevent the spread of a fire from the room below to the main ceiling above. In suspending the false ceiling, it is customary to support the fireproof panels on a rigidly connected framework of metal frame members having inverted T-shaped cross sections. The metal frame members usually expand when subjected to extreme heat from a fire. If the frame members are rigidly connected and not allowed to expand relatively to one another, the members often twist and buckle. Such distortion of the frame members may cause the fireproof ceiling panels to be tilted from their normal horizontal positions and may even allow the ceiling panels to fall from the framework, thus exposing the main ceiling to the fire.

False ceiling frameworks, termed fire-rated ceiling frameworks, allow longitudinal expansion of the frame members with respect to each other as a result of high temperatures from a fire. However, for the most part, these frameworks are diflicult to assemble and require specialized connections which increase the cost of assembly. Additionally, upon expansion. and subsequent contraction of the frame members of many previous firerated ceiling frameworks, the connections between the frame members become loose and sometimes allow the frame members to fall. It has been found that workmen engaged in renovation of ceilings after a fire have in some instances been seriously jeopardized by these loose connections between frame members. In order to repair these loose connections in fire-rated ceiling frameworks heretofore available, replacement of certain of the specialized connections is required and in same instances, Whole frame members may be required to be replaced.

Accordingly, a general object of the present invention is the provision of an improved fire-rated ceiling framework which substantially eliminates the disadvantages of ceiling frameworks heretofore available. The present invention provides a fire-rated ceiling framework which eliminates buckling of the frame members by accommodating longitudinal expansion of the members due to heat from a fire. Further, the instant invention provides secure connections between frame members which remain secure even after longitudinal expansion due to heat from a fire and longitudinal contraction resulting from cooling. Thus the ceiling framework of the present invention may in some instances be reutilized after a fire, and does not 3,378,976 Patented Apr. 23, 1968 require the replacement of additional parts after expanslon.

In achieving these and other objects that will be apparent hereafter, the present invention comprises a connection between a main frame member and two cross frame members which extend substantially normally to the main frame member. Each of the frame members has a horizontal base and vertical web arranged so that the cross section of the members is in the shape of an inverted T. The main frame member has an aperture formed in its web and the cross frame members include longitudinal end portions which extend through the aper ture in a side-by-side relationship in order to connect the members together. Each of the end portions has two faces, one of which is notched to prevent withdrawal of the end portion from the aperture. A projection extends from one of the frame members and abuts the adjacent frame member in order to normally restrain relative movement between the frame members. Additionally, the projection is defiectable to allow the cross frame members to expand longitudinally through the aperture in response to heat from a fire.

The invention and its many advantages will be further understood by reference to the following detailed descrip tion of several modifications illustrated in the following drawings, in which:

FIGURE 1 is an exploded perspective view, with portions of the structure broken away, of a connection of the fire-rated ceiling framework according to the invention;

FIGURE 2 is a perspective view of the embodiment of the present invention shown in FIGURE 1, after the occurrence of expansion resulting from abnormal thermal conditions; and

FIGURE 3 is a perspective view of the assembled ceiling framework comprising the frame members shown in FIGURE 1.

Referring now to FIGURE 1, a ceiling framework is illustrated which is comprised of a main frame member 97 and a pair of

cross frame members

106 and 108. As will be understood by one skilled in the art, a ceiling framework for an entire room would consist of a plurality of similar main frame members extending entirely across the ceiling and connected by a plurality of spaced apart cross frame members.

An embodiment of the present invention is shown in FIG. 1, wherein a main frame member 97 of the inverted T-type includes horizontal base flanges 98 and a vertical web 99 with an aperture 100 therein. The aperture comprises a narrow slotted bottom portion 102 and a downwardly extending interlocking member 104.

Two

cross frame members

106 and 108 extend perpendicularly to the main frame member at aperture 100 for passage therethrough. It will be understood that main frame member 97 includes throughout its length at spaced intervals a plurality of similar apertures with corresponding pairs of cross frame members. The

cross frame members

106 and 108 are of an identical inverted T-type configuration, and like reference numbers will be used to refer to like and corresponding parts in the drawings. Each cross frame member is comprised of a horizontal base 109 and a vertical web 110 with a longitudinal end portion 111 designed to fit through aperture 100 and to be fastened therein in an interlocking relationship. In order to provide for a secure fit within the aperture, end portions 111 are slightly laterally offset from the webs 110 and the combined thicknesses of the end portions are substantially equal to the width of bottom portion 102 of aperture 100.

Disposed on the lower face of each longitudinal end portion is a stop means 112 which normally abuts the base of the narrow slotted bottom portion 102 when the end portion is interlocked within the aperture. The upper face of each of the longitudinal end portions 111 includes a compound shoulder comprised of an abutment 114 and an inclined surface 116. Disposed above and thus extending longitudinally over each end portion is an elongated deflectable projection 118 which is particularly adapted to bend during longitudinal expansion of the cross frame members during abnormal thermal conditions. A vertical abutting edge 120 is provided on each projection in order to abut one side of the downwardly extending interlocking member 104 during normal conditions.

Formed along the side of each longitudinal end portion is an elongated embossment 122 which extends outwardly in order to abut the sides of aperture 100 to prevent lateral movement of the end portions once they are fastened within the aperture. As may be seen from the drawings, the lateral dimension of rib 122 is greater than the distance between the side of the aperture 100 and a line drawn from the upper to the lower face of the tongue, the tongue being resiliently deformed or flexed laterally by the engagement of the rib 122 with the side of aperture 100 until engagement is achieved between interlocking member 104 and the

shoulders

114 and 120. It will be obvious that the position and shape of this embossment may be changed in order to provide additional support against lateral bending or flexing of the longitudinal end portions if desired. At the termination of the horizontal base 109 of each of the cross frame members is disposed a camming surface 124 which normally rests upon the base portion of the main frame member when the cross frame member is interlocked within aperture 100.

Referring to FIGURE 1 the longitudinal end portions of the cross frame members will have to be slightly canted in order to initially move past interlocking member 104 during insertion. When abutment 114 has been pushed past interlocking member 104, the end portion 111 may then be straightened to a vertical position with interlocking member 104 fitting down within the notch defined by abutment 114 and edge 120. FIGURE 3 shows the assembled frame members wherein abutment 114 of member 106 is disposed against interlocking member 104 and the edge 120 of member 108 abuts interlocking member 104. The camming surface 124 of the base of the cross frame members rests upon the base flanges 98 of the main frame member to provide a secure connection of the frame members.

Upon the occurrence of high temperatures resulting from a nearby fire, the

cross frame members

106 and 108 tend to expand and to move longitudinally through aperture 100. In order to allow this expansion, the deflectable projection 118 will then bend laterally in the manner shown in FIGURE 2. The camming surface 124 rides up the base flange 98 of the main frame member and stop 112 climbs the base of aperture 100 during the expansion, thus providing an upward movement of the cross frame members. This upward movement is accommodated by the inclined face 116, which rides up the interlocking member 104.

This embodiment of the present invention will provide a secure interconnection between the frame members even during expansion because of the tensioning force applied by the bending deflectable projection 118. Further, the vertical force applied by the interlocking member 104 against the inclined surface 116 will provide a downward tensioning force which affords an improved connection during a portion of the longitudinal expansion. Additionally, upon cooling, and subsequent contraction, the cross frame members will again be restrained from withdrawal from the aperture 100 by the abutment 114, thus providing a secure framework after a fire.

From the foregoing description, it will be apparent that the ceiling support system of the present invention features main frame members which are normally securely fastened to a plurality of cross frame members at spaced intervals. When an abnormal ambient temperature condition arises because of the presence of a nearby fire, the resulting longitudinal expansion of the cross frame members is accepted by the main frame member without a subsequent buckling of the cross frame members. By eliminating buckling of the members, the ceiling panels supported by the frame members are maintained in their normal horizontal positions without being displaced vertically and thus interrupting the normal ceiling surface which serves as a fire wall. In addition, the present invention envisions a connecting construction which allows a restraining force to be placed on the cross frame members at all times for maintaining a secure connection to the main frame members. Further, the present invention enables secure connections to be made very simply and with a minimum of extra parts.

It will be apparent to those skilled in the art that various other modifications within the sphere and scope of the invention are possible. Therefore, the invention should not be deemed to be limited by what has been shown and described herein by way of example.

I claim:

1. A ceiling suspension grid comprising:

a main frame member having an upright section with an elongated upright aperture therein, said aperture being narrow at one end and appreciably wider at the other end,

said frame member having a tab integral with said upright section and projecting lengthwise into the wider end of said aperture and, said tab being spaced from the adjacent sides of said aperture,

a plurality of cross frame members each having an upright section and a tongue on the end thereof, the lower edge of each tongue being seated in and substantially filling one-half of the narrow end of said aperture,

each of said tongues having a portion on one edge thereof formin an outwardly facing shoulder for limiting the insertion of said tongues into said aperture by abutment of said shoulder against the upright section of said main frame members,

each of said tongues having an inwardly facing shoulder between said outwardly facing shoulder and the free end of said tongue, said shoulders being spaced apart sufficiently to receive said tab therebetween in locking engagement when the tongue of said cross member is inserted in said aperture, and

means on said tongue for bearing against a side of the aperture intermediate the ends thereof for maintaining the tongue in locking engagement with the tab.

2. A ceiling suspension grid as in claim 1, each of said tongues having a rib extending lengthwise alone one side thereof, said rib abutting against one side of said aperture in position upon insertion of said tongue therein to cause the lateral deflection of said shoulders into locking engagement with said tab whereby said cross members are held attached to said main frame members.

3. The grid of claim 1 wherein the portion of said tongue forming an outwardly facing shoulder for limiting the insertion of said tongue into said aperture is laterally deflectable under the pressure of longitudinal expansion of said cross frame members due to the heating thereof.

4. A ceiling suspension grid comprising:

a plurality of main frame members each forming an inverted T in cross section and having a flange and an elongated aperture in the vertical section thereof, said aperture having a narrow lower end an an appreciably wider upper end,

each of said main frame members having a tab integral with said section projecting vertically downward into the upper end of said aperture and spaced from the adjacent sides thereof, and

a plurality of cross frame members each forming an inverted T in cross section and having a flange and a portion of the vertical section thereof extending beyond said flange to form a tongue at each end thereof, the upper edge of said tongue having a vertical notch, the lower edge of said tongue being seated in said aperture, said flanges being in substantially coplanar relationship,

each of said tongues having a rib extending lengthwise along one side thereof, said rib abutting against one side of said aperture to maintain registration between said tab and said notch.

5. A ceiling grid suspension system comprising:

a plurality of main frame members each forming an inverted T in cross section and having a flange and an elongated aperture in the vertical section thereof,

said main frame members having a tab projecting vertically into said aperture from one end thereof, said tab being spaced from the sides of said aperture,

a plurality of cross frame members each forming an inverted T in cross section and a flange and vertical section with a tongue formed on each end thereof, said tongues being an extension of the vertical section of said cross frame members, said tongue having a reduced height portion in one edge thereof, and

means on said tongue responsive to the insertion of said tongue into said aperture for maintaining the vertical alignment of said tab and the reduced height portion of said tongue whereby said cross frame members are secured to said main frame members upon insertion of said tongue into said aperture and with tab and said tongue nonaligned with said reduced height portion thereof.

6. The system of claim 5 wherein said means comprises an elongated rib along said tongue, said rib extending laterally sufliciently to interact with a side of said aperture for urging the vertical alignment of said tab and said tongue. 2

7. The system of claim 5 wherein said means comprises a projection integral with the vertical section of said main frame member extending laterally into said aperture sufficiently to interact with said tongue to urge the vertical alignment of said tab and said tongue.

8. A ceiling suspension grid comprising:

a main frame member of substantially inverted T-shape having a flange and an upright section with an elongated upright aperture therein, said aperture being narrow at one end and appreciably wider at the other end,

a tab integral with said main frame member and projecting lengthwise into the wider end of said aperture, the edges of said tab being spaced from the adjacent sides of said aperture,

a cross frame member of substantially inverted T-shape having a flange and an upright web and a tongue on the end thereof, said tongue being seated in the narrow end of said aperture with the flanges of said main frame member and cross frame member in substantially coplanar relationship,

said tongue having a portion on one edge thereof forming an outwardly facing shoulder limiting the insertion of said tongue into said aperture by abutment of said shoulder against the upright section of said main frame member and an inwardly facing shoulder between said outwardly facing shoulder and the free end of said tongue, said tab being seated between said shoulders and preventing the withdrawal of said tongue from said aperture, and

means on said tongue engaging the side of said aperture intermediate the ends thereof maintaining the tongue contiguous to the center of said aperture.

9. The grid of claim 8 wherein said means includes an elongated rib integral with said tongue.

10. The grid of claim 9 wherein the lateral extension of said rib from said tongue is greater than the distance between the side of said aperture and a line drawn between the edges of said tongue whereby said tongue is resiliently deformed laterally intermediate the edges thereof by the insertion of said tongue into said aperture, said deformation being removed by the seating of said tab between said shoulders.

11. The grid of claim 10 wherein said rib extends to a point intermediate said inwardly facing shoulder and the rec end of said tongue whereby said tongue may be initially inserted undeformed into said aperture until said rib engages the side thereof.

12. The grid of claim 11 wherein the flange of said cross frame member overlaps a portion of the flange of said main frame member and wherein the portion of said tongue forming an outwardly facing shoulder for limiting the insertion of said tongue into said aperture is laterally defiectable under the pressure of longitudinal expansion of said cross frame members due to the heating thereof.

References Cited UNITED STATES PATENTS 1,053,129 2/1913 Holland 52-668 X 3,177,990 4/1965 Flucker et al. 52-668 X 3,189,139 6/1965 Znamirowski 52573 3,193,063 7/1965 Bronn et al. 52667 3,290,075 12/1966 Jahn 52484 3,292,332 12/1966 Jahn 52-484 3,312,488 4/1967 Lickliter et al. 287189.36

FOREIGN PATENTS 809,058 2/ 1959 Great Britain. 1,263,407 5/1961 France.

HENRY C. SUTHERLAND, Primary Examiner.