Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
PREASSEMBLED FASTENING ELEMENT
Document Type and Number:
WIPO Patent Application WO/1996/011311
Kind Code:
A1
Abstract:
A fastening element (10) includes a large washer (14) and a screw (12), which are preassembled at a right angle. The washer (14) is fixedly attached to the screw (12) at a preselected position in a mid-region of the screw (12). The screw (12) includes a drill tip (16) at its free end and a threaded shank (22). The other end of the screw (12) terminates in a screw head (18) which may be turned by a manual tool or a power tool. The aperture (26) in the washer (14) has an axially extended collar (38) that allows for a close sliding fit between the screw (12) and washer (14), and an adhesive material fixes the washer (14) to the screw (12) along the length of the collar (38) and holds the preassembled condition after manufacture until installation at a construction site. For installation, turning forces applied by a tool on the screw head (18), break the bond of the adhesive and permit the screw (12) to move through the washer (14). Alternatively, the aperture in the collar is threaded. Thereby, the screw and washer are tightly joined together by the engaged threads and an adhesive.

Inventors:
MOSSMAN, Jeffrey, L.
Application Number:
PCT/EP1995/003942
Publication Date:
April 18, 1996
Filing Date:
October 06, 1995
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
SFS INDUSTRIE HOLDING AG.
International Classes:
E04D3/36; E04D5/14; F16B43/00; (IPC1-7): E04D3/36; E04D5/14; F16B43/00
Foreign References:
US4809568A
GB1229922A
DE4239339A1
GB1386003A
NL7415863A
US4793757A
US3212387A
Download PDF:
Claims:
Claims
1. A preassembled fastening element to attach sheeting onto a solid substructure, compri a screw including a shaft having opposite ends and a thread extending over at least a po of the screw length, and a screw head connected at one said end of said shaft; a wa having an aperture, said screw shaft extending through said aperture, said aperture in washer being at least partially surrounded by a collar, said screw shaft extending thr said collar, the washer being at a distance from the screw head; and holding m including an adhesive at an interface between said screw and said collar for preve rotation and translation of said washer on said screw shaft prior to installation of fastening element to attach said sheeting.
2. A preassembled fastening element as in claim 1 , wherein said holding means for preve rotation and translation of said washer includes threads on an inner surface of said c said collar threads engaging said screw threads with one of a forced fit and a running fi.
3. A preassembled fastening element as in claim 1 , wherein said adhesive fills spaces w said collar between said collar and said screw threads.
4. A fastening element as in claim 1 , wherein said washer is at a preselected position on shaft.
5. A fastening element as in claim 2, wherein said washer is at a preselected position on shaft.
6. A fastening element as in claim 3, wherein said washer is at a preselected positioin on shaft.
7. A preassembled fastening element as in claim 1 , wherein said screw further includes a tip at the other of said ends of said shaft.
8. A preassembled fastening element as in claim 1 , wherein said aperture is centrally locate said washer and surrounded by a planar hub, said collar extending transversely from hub, a planar rim defining the outer periphery of the washer, and undulating ridges bet said hub and said rim, said ridges encircling said aperture.
9. A preassembled fastening element as in claim 1 , wherein said washer is one of metallic and nonmetallic.
10. A preassembled fastening element as in claim 3, wherein said adhesive is cyanoacrylate.
11. 1 1.
12. A preassembled fastening element as in claim 1 , wherein said collar overlays at least two turns of said thread on said screw shaft.
13. A preassembled fastening element as in claim 2, wherein said collar threads engage at least two turns of said thread on said screw shaft.
14. A preassembled fastening element as in claim 3, wherein said collar overlays at least two turns of said thread on said screw shaft.
15. A preassembled fastening element as in claim 1 , wherein said washer extends at substantially a right angle to a longitudinal axis of said screw.
16. A preassembled fastening element to attach sheeting onto a solid substructure, comprising: a screw including a shaft having opposite ends and a thread extending over at least a portion of the screw length, and a screw head connected at one said end of said shaft; a washer having an aperture, said screw shaft extending through said aperture, the washer being at a distance from the screw head; and adhesive means at said aperture for joining said screw and said washer to prevent rotation and translation of said washer on said screw shaft prior to installation of said fastening element to attach said sheeting.
17. A fastening element as in claim 15, wherein said washer is at a preselected position on said shaft.
18. A preassembled fastening element as in claim 15, wherein said screw further includes a drill tip at the other of said ends of said shaft.
19. A preassembled fastening element as in claim 15, wherein said adhesive means includes cyanoacrylate.
20. A preassembled fastening element as in claim 15, wherein said washer extends at substantially a right angle to a longitudinal axis of said screw.
Description:
Preassembled fastening element

The invention pertains to a fastening element including a screw and a large-surfaced metallic washer used to attach insulation material, and waterproofing membrane, onto a solid substructure. The screw is provided with a drill tip, a shaft with a thread that extends over at least part of its length, and a screw head. The washer is provided with a preferably central aperture in order to receive the screw shaft.

It is important to contractors in the field that the fasteners be preassembled, that is, with the washer attached to the screw. This facilitates rapid assembly, for example, installation of insulation layers on a roof top that has been prepared to receive the insulation. Because power tools are used in driving the screw into the substructure, it is most desirable at the start of installation that the washer of each fastener be at the same position on the screw in every instance. Then assembly becomes more routine and the time for assembly is more predictable.

The invention is generally used with an installation device to screw-in such a fastening element. The device typically has a support surface for the washer as well as a receptacle tube to receive the end of the screw at which the screw head is located. The receptacle tube is additionally constructed as a receptacle for an axially movable and rotatable tool to take hold of the screw head and to drive the screw into the substructure.

Fastening elements of the previously mentioned type are known in many different variations (for example, US Patent No. 4,781 ,503 and in pending U.S. application, S.N. 08/068,391 , filed May 28, 1993). One of the purposes of these prior art fastening elements is to securely retain a large-surface washer against axial movement in the immediate area of the screw head or in a threadless shaft section located directly beneath the screw head. This positioning is intended to yield a certain degree of safety against loads, for example, people walking on the insulation sheeting, or on the waterproof sheeting applied on top of the insulation sheeting, during utilization of such fastening elements on roof surfaces. In other words, it is desirable that screw head penetration towards the outside through the waterproof sheeting be prevented, if such a walking load is applied.

One known variation of a fastener element utilizes a plastic disk as the large-surface washer. plastic disk is braced against a peripheral collar arranged on the screw shaft. A different vari of a fastener element utilizes a metallic washer, which is braced against the end of the thre section, provided adjacent to the screw head.

US Patent No. 4,809,568 introduced a fastening element and a device designed to screw-in fastening element. This known fastening element comprised a screw and a plastic washer. washer had an extended hub in its central area proximate an aperture provided for insertio the screw shaft so that the wall of the aperture adjoins the screw threads over a relatively section. The fastener may be threaded into the washer and will remain in this positio preassembled condition until the final mounting process, because of the correspondingly s dimensions of the aperture in the washer.

However, it is, in practical applications, not always possible to utilize plastic washers particular in those sections of a roof where a subsequent waterproofing is performed by m of a flaming process. It is desirable, and at times a requirement that large-surface met washers be utilized in such instances.

In order to facilitate preassembly of a washer on a screw at a distance from the screw hea has been attempted to inject a plastic part into a larger central aperture of the washer, whe the injected plastic part adjoins the screw over a certain threaded area, thus making preasse possible. However, it was soon determined that such an additional central plastic part metallic washer incurs very high costs, thus representing a very disadvantageous factor for produced articles of this type.

In order to screw-in such fastening elements with a practical hand tool, it is necessary that large-surface washer be positioned on the screw shaft at a substantially large distance from screw head, if an axial alignment of the screw is to be obtained while screwing in the faste element. That is, it is desirable that the screw enter the substructure at a right a (90 degrees) and that the general plane of the washer be at a right angle with the screw sha

This axial alignment is obtained by the screw head engaging into the driving tool on the hand, and by guiding the screw in the aperture of the washer on the other hand, so that at l two-point guidance exists until the tip of the screw penetrates the solid substructure.

An object of the invention is to provide an improved preassembled fastening element, including a screw and a metallic washer, that is optimally suitable for a special fastener.

Another object of the invention is to provide an improved preassembled fastening element that maintains a proper orientation of washer and screw after manufacture and during installation.

Yet another object of the invention is to provide an improved preassembled fastening element that is economical to produce.

Still another object of the invention is to provide an improved preassembled fastening element which maintains a selected fixed relative position between the screw and washer of the fastening element prior to installation of the fastening element.

In accordance with the invention, a fastening element includes a large washer and a screw, which are preassembled so that the washer is at a right angle to the longitudinal axis of the screw, and the washer is fixedly attached to the screw at a preselected position in a mid-region of the screw.

The screw includes a conventional drill tip at its free end and a threaded shank, which may be fully threaded, or to decrease production cost is only partially threaded. The other end of the screw terminates in a screw head which may be turned by a manual tool or a power tool, preferably in conjunction with a guiding and retaining fixture or attachment jig. The jig assures the desired right angle entry of the screw into the substructure while the washer is maintained at a right angle to the screw shank. Such an attachment jig is described in the above-mentioned pending application, which is hereby incorporated by reference.

In one embodiment of a fastening element in accordance with the invention, the aperture in the washer has an axially extended collar that allows for a close sliding fit between the screw and the washer. An adhesive material fixes the washer to the screw along the length of the collar and holds the preassembled condition after manufacture until installation at a construction site. However, for installation, turning forces, applied by a tool on the screw head, break the bond of the adhesive and permit the screw to move through the washer, preferably, while the screw head is retained in a guiding jig to maintain right angle orientation during the driving procedures.

In another approach, the aperture in the collar is threaded and is small in diameter relative t screw thread height diameter such that the screw and washer are tightly joined together b engaged threads and an adhesive, and hold a fixed position until the screw is driven relati the washer by a tool.

The fastening element in accordance with the invention is not limited in its uses to ro constructions but may be used wherever a sheet material or sheeting, regardless of thick and rigidity or flexibility, must be attached to a supporting structure.

The invention accordingly comprises the features of construction, combinations of elements, arrangement of parts, which will be exemplified in the constructions hereinafter set forth, the scope of the invention will be indicated in the claims.

For a fuller understanding of the invention, reference is had to the following description tak connection with the accompanying drawings, in which:

Fig. 1 is a front elevational view, in section, of a preassembled fastener in accordance with invention;

Fig. 2 is a bottom view of the washer in the fastener of Fig. 1 ;

Fig. 3 is an elevational view, in section, of a fastener of Fig. 1 after installation to retai insulation panel on a substructure;

Fig. 4 is a fragmentary view similar to Fig. 1 , to an enlarged scale, of a first embodiment of invention; and

Fig. 5 is a view similar to Fig. 4 of an alternative embodiment in accordance with the inventi

With respect to the figures, a preassembled fastening element 10 in accordance with invention includes a screw 12 connected to a washer 14. The screw is in four portions inclu a drill tip 16 at one end, and a screw head 18 at the other end of the screw 10. The illustr screw head 18 is hexagonal in cross section and would be turned with a plier-type or wrench or a socket wrench adapted to operate with the hex head. Note that any head including a means for power or hand driving is acceptable.

The screw also includes an unthreaded shank 20 adjacent to the screw head 18, and a threaded shank portion 22. An integral washer 24 connected to the screw head 18 and to the unthreaded shank 20, provides for an aligned sliding fit of the screw in a fastening tool, for example, as in the above-referenced pending patent application.

The washer 14 is circular in shape and has a central aperture 26 wherethrough the screw 12 passes, as described more fully hereinafter, and is positioned in the preassembled condition. The washer 14 lies generally in a plane that is perpendicular to the longitudinal axis 28 of the screw 12. The washer 14 includes a central planar hub 30, a peripheral and coplanar rim 32, and a plurality of undulated ridges 34 positioned between the hub 30 and rim 32, concentrically with the aperture 26. The ridges 34 provide rigidity in the washer 14, which is preferably made of metal although plastic is also suitable. The undulating ridges 34 and their trough surfaces 36 provide an enlarged contact area with the insulation material and provide increased resistance to back-out of the fastening assembly 10 after installation.

As illustrated in Fig. 4, the generally planar hub 30 connects to an axially extended collar 38 that includes internal threads 40 engaging external threads 42 on the screw 12. An adhesive 46 fills the interstices between the threads. The threads 40, 42 and adhesive 46 engage with a tight fit so that it is necessary that a substantial external force be applied to thread the washer 14 along the screw 12 to the preselected position, as illustrated in Fig. 1. That is, the connection between the screw 12 and the washer 14 is more than finger-tight; a driving tool or wrench may be required to preset the position of the washer 14 on the screw before the adhesive 46 is added. In this regard, the threads 42 on the screw 12 may be of the type that taps threads into a blank collar 38 upon initial assembly of the washer 14 onto the screw 12.

These tight fitting threads 40, 42 and adhesive assure that the fastening element 10 in accordance with the invention can be preassembled at a factory and shipped to the site without change in the position of the washer 14 along the length of the screw 12. At least two screw threads 40 on the collar 38 are in engagement with the threads 42 on the screw 12. This assures that the washer 14 is at the preferred right angle 43 to the longitudinal turning axis 28 of the screw 12. A right angle entry of the screw 12 into the substructure 52 (Fig. 3) is important and this is facilitated when the washer 14 first rests upon the insulation material with the screw only partially penetrated and not yet in contact with the substructure.

Fig. 5 illustrates an alternative embodiment of a fastening element in accordance with invention wherein the collar 38' is of larger diameter (compared to the embodiment of Fig. 4) unthreaded on its internal surface 44 such that the screw can slide through the collar 38' w close fit. When the screw 12 and washer 14 are at the desired relative positions, as indicat Fig. 1 , an adhesive 46 is applied to fill the collar. The adhesive hardens and holds the wa and screw in fixed relative positions. The holding strength of the adhesive is such that s mechanical advantage, either from a wrench or a power tool, is necessary to rotate the s relative to the washer. Finger force is insufficient. Thus, the adhesive 46 serves to maintain preassembled condition of the fastener assembly, just as the interference threads 40, 42 adhesive serve the same function in the embodiment of Fig. 4.

Many adhesives are available for joining the washer and screw during manufacture. Fixtur curing time is an important consideration in selecting an adhesive. Hot melt, UV-cured anaerobic are some types of adhesive that may be used. Paints and varnishes, and the like, serve but are slower in drying. A cyanoacrylate adhesive manufactured by Loctite Corpora has been used with good results.

The sleeve 38' in another alternative embodiment may have running threads (not shown) o inner surface to loosely engage the screw threads 42. However, fixed positioning on the scre achieved with the adhesive 46.

As is known in the art, the screw 12 may have another unthreaded portion between unthreaded portion 20 and the drill tip 16. This additional unthreaded portion, in a preassem fastening element 10, may be located between the extreme edge 48 of the sleeve 38 and drill tip 16. Elimination of a portion of the threads on the screw reduces production c However, sufficient length of threads must be maintained proximate the drill tip 16 as it is t initial threads 42 that engage the substructure and hold the entire fastening element 10 and insulation in place. However, in leaving unthreaded portions, it is important to maintain a c alignment between the collar 38, 38' and the threads 42, either by way of the inte threads 40 or the close sliding fit with the inner surface 44, so that the right angle align between screw and washer is maintained until the threads adjacent the drill tip have engaged substructure.

The unthreaded portion 20 is limited in length to restrict motion of the washer along the scre someone should walk on the washer after installation.

in using the fastening assembly, for example, in attaching (Fig. 3) an insulation layer 50 to a roof, a corrugated substructure 52 is first attached to the roof. Then the insulation layer 50 is placed upon the substructure 52 and a fastening assembly 10 is connected for rotation to an installation tool. The drill end 16 of the screw 12 is pressed into the insulation 50 until the washer 14 makes contact with the upper surface 54 of the insulation layer 50. Thereby, the washer is restrained from turning by friction, especially at the hub 30, rim 32 and low points 36 on the upper surface of the insulation layer.

As the screw 12 continues to be turned by the driving tool and the washer is restrained by friction from turning with the screw, the screw further penetrates the washer by breaking the adhesive bond and also overcoming the friction of the threads 40, 42. The screw is advanced until the drill tip 16 engages and forms an opening 56 in the substructure 52. Rotation of the screw continues until the threads 42 on the screw 12 engage in the substructure and until the desired compression of the washer 14 into the upper surface 54 of the insulation layer 50 is achieved. Generally, substantially the entire undersurface of the washer 14 is in frictional contact with a somewhat deformed upper surface 54 of the insulation layer 50. In many applications, a waterproof membrane (not shown) is provided over the insulation layer and generally covers the protruding screw head 18.

The collar 38, in its final installed position, is riding along the unthreaded portion 20 of the screw. However, axial motion of the washer along the length of the screw is limited by the start of the threads 42. Thus, the screw head is less able to pop out through the membrane when someone walks on the insulation layer, and the relative positions between the screw and the washer are maintained.

It will thus be seen that the objects set forth above and those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.




 
Previous Patent: PANEL-SECURING SYSTEM

Next Patent: STANDING SEAM ROOFING PANEL