US 3855750 A
The embodiment of the invention disclosed herein is directed to a screw assembly comprising a cylindrical shank having a thread formed therealong and a conical head formed at the trailing end of the shank with slot means formed in the head for receiving a driving tool. An annular flange is formed at the top of the conical head and cooperates with a conical washer to form an annular groove or undercut between the flange and paper surface of wallboard when the screw is driven home firmly to hold the wallboard to support studs or the like. When the screw assembly is fully driven home, it forms an outwardly diverging depression about the screw head with the top surface of the screw head beneath the surface of the wallboard. A quantity of topping compound is applied over the screw head into the diverging depression completely to cover the screw head from view. The annular groove formed by the flange and the conical washer allows a quantity of the topping compound to flow therein thus providing a more secure bond of the topping compound patch so that flaking and chipping will not occur.
Description (OCR text may contain errors)
llnited States Patent Reiland Dec. 24, 1974 SCREW ANCHORED WALLBOARD ASSEMBLY  Inventor: Bernard F. Reiland, Rockford, Ill.
 Assignee: Textron, Inc., Providence, R.I.
 Filed: Jan. 15, 1973  Appl. No.: 323,879
 US. Cl 52/363, 52/715, 85/41,
85/50  Int. Cl..... E04b 2/58, F16b 25/00, F16b 39/26  Field of Search 52/418, 210, 213, 214,
 References Cited UNITED STATES PATENTS 156,699 11/1874 Fuller 85/50 R 1,564,455 12/1925 Stanbro 52/362 1,672,099 6/1928 Schumacher 52/361 2,157,374 5/1939 Wells 52/363 3,298,270 l/1967 Launay 85/50 R 3,322,019 5/1967 Lovisek 52/363 3,556,570 l/l971 Cosenza 85/50 R FOREIGN PATENTS OR APPLICATIONS 1,322,847 2/1963 France 85/50 R 1,068,245 5/1967 Great Britain 85/41 Primary Examiner-Henry C. Sutherland Attorney, Agent, or Firm-Ols0n, Trexler, Wolters, Bushnell & Fosse, Ltd.
[ ABSTRACT The embodiment of the invention disclosed herein is directed to a screw assembly comprising a cylindrical shank having a thread formed therealong and a conical head formed at the trailing end of the shank with slot means formed in the head for receiving a driving tool. An annular flange is formed at the top of the conical head and cooperates with a conical washer to form an annular groove or undercut between the flange and paper surface of wallboard when the screw is driven home firmly to hold the wallboard to support studs or the like. When the screw assembly is fully driven home, it forms an outwardly diverging depression about the screw head with the top surface of the screw head beneath the surface of the wallboard. A quantity of topping compound is applied over the screw head into the diverging depression completely to cover the screw head from view. The annular groove formed by the flange and the conical washer allows a quantity of the topping compound to flow therein thus providing a more secure bond of the topping compound patch so that flaking and chipping will not occur.
3 Claims, 3 Drawing Figures lllllllll' SCREW ANCHORED WALLBOARD ASSEMBLY BACKGROUND OF THE INVENTION This invention relates generally to fasteners, and more particularly to fasteners of the type used to secure wallboard such as drywall to supporting studs.
The present invention contemplates the method of forming a wall structure wherein plasterboard is secured to upstanding wood or metal studs. Heretofore plasterboard has been traditionally nailed in place when positioned over wooden support studs. The nail heads are recessed a slight distance beneath the surface of the wallboard as a result of an over extended hammer blow which sets the nail slightly beneath the surface. A quantity of plaster patch or plaster-like material commonly referred to as topping compound is applied over the nail head to fill the depression so that a smooth wall surface is the visual result. However, with the increase use of metal support studs nailing in this fashion is not advisable. To firmly secure wallboard to such metal studs a power driven threaded screw is commonly used and driven home by a pnuematic or electric drill which has a slip clutch mechanism set at a predetermined torque condition. When the screw is inserted through the wallboard and threaded into the metal stud it is driven home to a condition where the top surface of the screw is recessed beneath the surface of the wallboard. This condition causes an outwardly diverging depression to occur around the screw head similar to the depression formed by the over extended hammer blow, and this depression is filled in with the topping compound as mentioned above.
However, problems have occurred in the use of such threaded power driven screws in that the twisting action of the screw head just as it is driven home against the paper surface of the wallboard tends to twist and tear the paper surface. This condition produces an undesirable appearance and weakens the ultimate connection therebetween. Also, as a result of vibration, thermal expansion, and other phenomenon the plaster patch over the screw head sometimes flakes or chips away because of poor gripping action of the plaster patch over the screw head.
SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a new and improved screw assembly for use in forming drywall structures which screw assembly will not twist or tear the paper surface of the drywall when driven home and which will provide improved gripping action of the plaster patch formed over the head of the screw.
Another object of this invention is to provide an improved screw assembly which is efficient and reliable in use but which is simple and inexpensive to manufacture.
Many other objects, features and advantages of this invention will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings wherein like reference numerals throughout the various views of the drawings are intended to designate similar elements and components.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary view showing a wall structure constructed in accordance with the principles of this invention;
FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and showing the details of the screw assembly of this invention; and
FIG. 3 is a surface view of the wall structure showing a plaster patch covering the recessed head portion of the screw of FIG. 2.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to FIG. 1, there is seen a wall structure constructed in accordance with the principles of this invention and designated generally by reference numeral 10. The wall structure 10 is formed of a plurality of wallboard panels 12 which preferably are of plasterboard, or the like, and held in position by a plurality of screws 14 which pass through the wallboard panel and are threadedly inserted into vertical support studs 16. Here the support studs are metal but it will be understood that the screw assemblies of this invention may be incorporated in wood wall studs if desired. The wall structure 10 may be of any configuration and may include a door frame unit 17 as well as windows or the like, not shown.
The screw assembly 14 is best illustrated in FIG. 2. Here the screw assembly comprises a shank portion 20 having threads 21 formed therealong and a conical head 22 formed integral with the trailing end 21a of the shank 20. The conical surface 24 is directed toward the surface of the wallboard 12 while a flat top portion 26 of the head 22 is arranged so as to be beneath the surface of the wallboard when the screw 14 is driven fully home by an impact wrench, or the like, inserted into a tool receiving slot 28.
Most advantageously, an annular flange 30 is formed at the endmost portion of the conical head and cooperates with a conical washer 32 in a unique and novel manner. While the illustrated embodiment herein discloses an annular flange and conical washer, it will be understood that other topping compound gripping means may be incorporated about the periphery of the head 22 to cause plaster-like material to flow between the head and the paper surface of the wallboard. When the washer 32 is incorporated, it is provided with an aperture 34 centrally thereof and has axially extended portions 36 circumscribing the shank 20.
Preferably, the washer 32 is placed on the shank 20 before the threads 21 are formed thereon. The apertue 34 is therefore selected so as to be sufficiently large to fit easily over the shank 20 but of a size to be smaller than the major diameter of the threads after they are formed by a thread rolling process. By so forming the aperture smaller than the major diameter of the thread 21 the conical washer 32 is at all times positioned on the screw and therefore forms the screw assembly 14.
In accordance with this invention the washer 32 has a radial extent which is inwardly of the flange 30 to form a recess 38 which cooperates with the paper surface of the wallboard 12 to form an annular groove or undercut 40. The topping compound or plaster patch material which is used will flow into the annular groove 40 for a more secure bond.
When the screw assembly 14 is fully driven home it forms an outwardly diverging depression 42 about the screw head and causes linear stretch marks to form in the paper surface of the wallboard 12. These linear stretch marks are illustrated in FIG. 3. Therefore, by utilizing a conical washer to act as a bearing surface between the rotating action of the conical head of the screw and the paper surface of the wallboard, twisting and tearing of the paper does not occur.
The method of this invention is carried out by first placing wallboard over the studs in a predetermined orientation, they being either set in position vertically or horizontally, and then inserting a plurality of screw assemblies 14 through the wallboard and into the support stud for holding the wallboard in place. The screw assemblies are driven home to form the outwardly diverging depression 42 about the head portion. The method is further accomplished by placing a quantity of topping compound 44 in the outwardly diverging depression for covering the screw head and for allowing the topping compound 44 to flow into the annular groove 40 formed between the paper of the wallboard and the annular flange 30.
While a single specific embodiment of the screw assembly of this invention is illustrated it will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts disclosed and claimed herein.
The invention is claimed as follows:
1. In combination with a wall structure comprising a plurality of supporting studs over which sheets of wall board are secured; a screw assembly penetrating said wall board and holding the same to said studs, said screw assembly comprising a cylindrical shank having threaded means formed therealong for threading the screw assembly through a wall board panel and into engagement with one of said support studs, said cylindrical shank having a leading end inserted into the support stud and a trailing end spaced from said support stud, a conical head formed integral with said trailing end of said shank, a radially extending annular flange formed about said conical head, a washer carried on said shank and having a conical portion complementally engaged with said conical head and an aperture formed centrally therein to receiving said cylindrical shank, said conical washer portion having a wall thickness, a radial extent and an axial length such that the outer conical surface of said conical portion engages the adjacent wall board surface forming an outwardly diverging depression therein and the maximum diameter edge of said washer is spaced inwardly of the peripheral edge of said flange and inwardly of the adjacent wall board surface in the depression to cooperate with said radially extending flange to form an annular recess immediately adjacent said flange on the underside thereof, with the top surface of said conical head being disposed beneath the normal outer surface of said wall board and with the peripheral edge of said flange spaced inwardly of the adjacent wall board surface in the depression to provide access opening to said recess, and a topping compound patch filling said depression and covering said screw, said topping compound being flowed through said access opening into said annular recess and hardened to provide gripping anchorage means for maintaining said patch in place.
2. The wall structure according to claim 1, wherein said conical washer has an axially directed portion about said aperture.
3. The wall structure according to claim 2, wherein the diameter of said aperture is less than the major diameter of the threaded portion of said shank thereby preventing said conical washer from being removed from said shank.