Spring lock means for connecting abutting form panels

Abstract

A modular concrete wall form panel unit comprises a facing panel and a supporting frame of metal structural members having edge faces normal to the panel and flush with its edges. Adjoining panels are quickly fastened together and taken apart by captive T-head fasteners which extend through elongated slots in the edge faces and seat against spring pressure in cammed fittings when the T-head fasteners are rotated. Each fastener is provided with a second compression spring which retracts it within the frame when it is disengaged. Each unit is provided with slots extending across the edge faces of the frame and into the panel face as semicircles so that when adjoining panels are fastened together holes for tie rods are thereby formed.

Description

This invention relates to reuseable concrete wall form panel units comprising a facing panel affixed to a metal frame. It is more particularly concerned with such panels provided with mechanisms for fastening them together and for bracing them.

The use of modular concrete wall form panel units is well established in the building industry. Conventionally, those units are rectangular in shape and include a frame constructed of metal elements, frequently steel, supporting a facing panel, generally of plywood. The frames are provided with flanges or like planar edges around their peripheries and those flanges or edges carry means for fastening adjoining panels together. It is usually necessary to connect the forms for the opposite sides of a wall with tie rods so as to prevent spreading of the forms by the weight of the concrete, and holes are sometimes provided in the flanges through which those tie rods are assembled.

It is, of course, desirable to assemble or disassemble quickly a series of such panel units, and various types of fastening means have been devised to that end. Pin-and-wedge type fasteners of the type illustrated in U.S. Pat. No. 3,661,354 issued to R. T. Dagiel et al., on May 9, 1972 are widely used, but have the disadvantage that the pins and wedges are easily lost. A captive type of cam fastener is disclosed in U.S. Pat. No. 2,297,899, issued to H. Kruger on Oct. 6, 1942. Those fasteners, when unassembled, are loose in their sockets and may project beyond the edges of the panel, thus being subject to accidental damage. A spring retracted rotatable fastener is disclosed in U.S. Pat. No. 3,385,555 of J. R. Williams, dated May 28, 1968, but it is not a captive fastener and in that respect suffers from the above mentioned disadvantage of the Dagiel fastener.

It is an object of my invention to provide a modular concrete wall form panel unit having improved means for positioning tie rods therein. It is another object to provide such a panel having improved captive fastener means. Other objects of my invention will become apparent from the description thereof which follows.

An embodiment of my invention presently preferred by me is illustrated in the attached figures, to which reference is now made.

FIG. 1 is a side elevation of the frame of a panel unit of my invention;

FIG. 2 is an end elevation of FIG. 1;

FIG. 3 is a partial cross-section taken on the plane 3--3 of FIG. 1 showing the attachment of the plywood facing panel to the frame;

FIG. 4 is a detail of a portion of the fastener of my invention in its retracted position;

FIG. 5 is a detail of adjoining panels connected by the fasteners of my invention;

FIG. 6 is a partial cross-section taken on the plane 6--6 of FIG. 1 showing a portion of my fasteners; and

FIG. 7 is a developed view of a portion of a side member of the frame of FIG. 1 showing a tie rod slot.

My invention comprises a cross-braced rectangular metal frame of flanged elements having a plywood panel attached to the flanges on one side thereof, captive fastening elements attached to the edges of the frame at spaced intervals, and slots through those edges and a portion of the frame immediately adjacent thereto which with like slots in adjoining panels form holes for tie rods.

The frame 10 of my panel is formed of side uprights 11 and 12 and end cross-pieces 13 and 14. Although my panels may be used in any position I call cross-piece 13 a bottom cross-piece and cross-piece 14 a top cross-piece for the purpose of this description. The rectangular frame 10 so formed is braced by a plurality of horizontal braces 15 connecting uprights 11 and 12 and spaced from each other along those uprights. Upright 12 is channel-shaped as may be seen from FIG. 3, comprising a web 18 and flanges 19--19, and upright 11 is likewise a channel. Cross-pieces 13 and 14 and braces 15 are angles. A plywood panel 16 is fastened to frame 10 by screws 17 through holes in the flanges of the members constituting that frame.

Uprights 11 and 12 are provided with parallel-sided slots 21 cut entirely through web 18 transversely thereof and extending into flanges 19 as semi-circular holes 22. These are best illustrated in FIG. 7. The uprights of adjoining panel units are provided with similar mating cutouts and when the abutting panel units are joined together the resulting circular holes form apertures for ties of circular cross-section which are locked in place by conventional collars.

The webs of uprights 11 and 12 and the edge flanges of bottom and top cross-members 13 and 14 are pierced at spaced intervals with elongated openings 23. These openings have a circular center portion 24 which is extended along one diameter into oppositely positioned rectangular slots 25 of lesser width than the diameter of the center portion 24.

When adjoining panel units are aligned side-by-side or end-to-end, the elongated openings 23 of the abutting edge of one unit register with those of the abutting edge of the ajoining unit. The units are locked together with rotary cam-type fasteners consisting of a T-bolt element 27 and a cammed seat element 28. Alternate openings 23 around a panel unit are provided with T-bolt elements 27 and with cammed seat elements 28, so arranged that the T-bolt elements of one panel unit in their operative position can extend through the openings 23 and engage the cammed seat elements 28 of the adjoining panel unit.

A T-bolt 27 in its retracted position is illustrated in FIG. 4. It comprises a cylindrical shaft or shank 29 terminating at one end in a T-head 30, that head being formed by two oppositely projecting lugs 31 dimensioned to pass through slots 25, and terminating at the other end in an operating head 32 which is conventionally a hexagonal nut.

The T-bolts 27 are captive fasteners. Shank 29 passes through a clearance hole in a bearing member 33 which is affixed to flange 19 of the frame member, for example, channel 11, parallel to web 18 thereof but inboard thereof so that T-head 30 is on one side of member 33 and operating head 32 is on the other. The clearance hole in bearing member 33 is aligned with an opening 23 in the web 18 of channel 11. A pair of Belleville or cup washer springs 34 is positioned around shank 29 between T-head 30 and bearing member 33. A washer 36 is affixed to shank 29 between the Belleville springs 34 and bearing member 33. A helical compression spring 35 is likewise positioned around shank 29 between bearing member 33 and operating head 32.

A seating element 28 is shown in plan in FIG. 6. These elements are attached to the inside face of web 18 of frame members 11 and 12, and inside face of the edge flanges of cross-pieces 13 and 14. Each element is divided into quadrants, opposed quadrants 38, each of which is pierced by a slot 25 of opening 23, being ramp quadrants, and opposed quadrants 39 having bearing surfaces parallel to web 18 but spaced therefrom. The low edge 40 of each ramp quadrant 38 lies in the plane of web 18, for example, and along a side of slot 25. The high edge 41 of each ramp quadrant 38 is at the level at the bearing surface of quadrant 39. A shallow diametral groove 42 wide enough to accommodate lugs 31 of T-bolt 27 extends across bearing surface quadrants 39--39.

The panel units are connected together by aligning lugs 31 of T-bolt head 30 with slots 25 in opening 23 and pushing shank 29 until those lugs go through those slots. T-bolt 27 is then rotated clockwise, as shown in FIG. 6, by turning nut 32 with a wrench. This causes lugs 31 to travel up ramps 38, thus moving T-bolt 27 further toward seating element 28. This movement is resisted by the Belleville springs 34 which are compressed between washer 36 and web 18, as well as by compression spring 35 is compressed between nut 32 and bearing member 33. The connection is locked by rotating shank 29 until lugs 31 seat themselves in groove 42.

The panel units are disconnected by rotating nut 32 in the opposite direction. When lugs 31 are again aligned with slots 25 compression spring 35 expands, moving T-bolt 27 to the right as seen in FIG. 4. Spring 35 is dimensioned so that in its extended position it retracts T-bolt head 30 until its outer end is flush with or within web 18.

The Belleville springs 34 are by their nature stiff and exert considerable force when compressed only slightly. Therefore, the ramp quadrants 38 of seating element 28 need not provide for much axial movement of T-bolt 27 to maintain tension therein. The travel or extension of the Belleville springs between their compressed and uncompressed condition is insufficient to retract T-bolts 27 within frame 10. Spring 35 which is provided for this purpose is not required to tension T-bolts 27. Spring 35 is conveniently a conventional coil spring of much less stiffness but of much greater travel or extension than Belleville springs 34.

While I have described an embodiment of my invention in which uprights 11 and 12 of frame 10 are channel sections, those uprights could be angles, like cross-pieces 13 and 14, or those corss-pieces could be channels, like uprights 11 and 12.

In the foregoing specification I have described a presently preferred embodiment of this invention, however, it will be understood that this invention can be otherwise embodied within the scope of the following claims.

Claims

I claim:

1. In a modular concrete form panel unit comprising a facing panel, a peripheral frame attached thereto of members having planar edges normal to the panel positioned to abut the corresponding edges of adjoining units, elongated openings positioned in those edges to register with like openings in adjoining unit edges, circular cam elements disposed around certain of those openings on the inside face of the edge, and T-head fasteners adapted to extend through those registering openings and upon rotation engage the cam elements, the improvement comprising a washer on the T-head fastener shaft spaced from the T-head, a first compression spring positioned between the washer and a frame member edge, the spring being compressed when the T-head engages a cam element and having a travel when uncompressed less than that required to maintain the T-head fastener within the frame, a bearing member affixed to the frame member edge but spaced therefrom and having a hole through which the shaft of the T-head fastener extends, an operating head on the outer end of that shaft, and a second compression spring positioned between the bearing member and the operating head having a travel when uncompressed sufficient to maintain the T-head fastener within the frame.

2. The apparatus of claim 1 in which the washer is of greater diameter than the hole in the bearing member.

3. The apparatus of claim 1 in which the first compression spring is stiffer than the second compression spring.

4. The apparatus of claim 1 in which the cam elements comprise oppositely disposed ramps and flat portions and a diametral groove extending across opposed flat portions so as to form a seat for the T-head of a fastener.

5. The apparatus of claim 1 in which the first compression spring is a Belleville spring.

6. The apparatus of claim 1 in which the frame member is of channel cross-section, the channel web comprising the planar edge, and the bearing member forms with the channel a box section.