WO1996011088A1

WO1996011088A1 - Installation tool for preassembled fastening element

Info

Publication number: WO1996011088A1
Application number: PCT/EP1995/003943
Authority: WO
Inventors: Jeffrey L. Mossman
Original assignee: Sfs Industrie Holding Ag
Priority date: 1994-10-07
Filing date: 1995-10-06
Publication date: 1996-04-18
Also published as: AU3804495A

Abstract

An installation tool for preassembled fastening elements provides alignment between the washer and screw during installation and does not permit the washer to rotate with the screw. The tool has a backing surface for the washer and a guide tube to receive the head or shank of the screw. Magnets, embedded in the backing surface, retain a steel washer and screw fastener, fully assembled, in the tool. A plurality of pins near the circumferential perimeter of the backing surface have conical or bevelled surfaces, which together provide a self-centering cradle for the washer. The tapered pins make local contact with the circumferential edge of the washer. When the screw is rotated by a power tool connected to the fastening tool, rotation of the washer in the tool is prevented by interference between the washer's peripheral edge and the bevelled pin surfaces.

Description

Installation tool for preassembled fastening element

The invention relates generally to a preassembled fastening element including a screw and a large-surfaced metallic or plastic, e.g. a polymer, washer used to attach insulation material, and waterproofing membrane, onto a solid substructure. The invention relates more particularly to an installation device or tool to screw-in such a fastening element to make the attachment.

The installation device typically has a backing or support surface for the washer as well as a guide tube to receive the end of the screw having the screw head. The guide tube is additionally constructed as a receptacle for an axially movable and rotatable tool which takes hold of the screw head and drives the screw into the substructure. Such a device and an associated fastening element are described in application Serial No. 08/068,391 , filed May 28, 1993, which application is incorporated herein by reference. The referenced application and the present application have a common assignee.

The screw is provided with a drill tip, a shaft with a thread which extends over at least part of the shaft 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 at a substantially right angle to the screw. This preassembly facilitates rapid assembly, for example, installation of insulation and waterproofing layers on a roof top that has been prepared to receive an insulation/waterproofing system. Because power tools are generally used in driving the screw into the substructure in conjunction with the installation tool, 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.

When using the installation tool with a fastening element, the head end of the screw is held in the guide tube, and the drill end is pressed into the outer surface of the insulation layer until the washer is brought to bear on the outer surface of the insulation. Then, if the washer is prevented from rotating, further rotation of the screw head by the a power tool causes the screw to advance through the washer until the screw reaches the substructure where the drill tip penetrates, followed by the threaded shank of the screw. However, a problem arises when the washer is not suitably restrained from rotation as th leading end of the screw is pressed into the insulation layer. Then, the washer rotates and th screw does not properly advance through the washer toward the substructure, and the rotatin washer may score the surface of the insulation or waterproofing membrane.

This problem has become more significant in that new designs of fastening elements includ means, for example, an adhesive, to make the connection between the washer and the scre threads more resistant to relative motion of the washer about the screw axis.

What is needed is an installation tool that assures that the washer does not rotate with th screw during installation while the screw is rotated by a power device in an installation tool.

Accordingly, it is an object of the invention to provide an improved installation tool fo preassembled fastening elements, that assures proper alignment between the washer and th screw during installation and does not permit the washer to rotate with the screw or relative t the installation tool during the installation procedure.

The installation tool in accordance with the invention has a backing surface for the washer as well as a guide tube to receive the end of the screw having the screw head. The backing surface is surrounded by an extended collar to form a recess wherein the washer is seated. Magnets are embedded in the backing surface so as to better retain a washer and screw fastener, fully assembled, in the tool when the washer is formed of a magnetically attractive material, for example, steel.

A plurality of pins located near the circumferential perimeter of the backing surface and generally perpendicular thereto, have conical or bevelled surfaces. These bevelled surfaces together provide a self-centering cradle for the washer that is held by the tool, and by the magnets when using steel washers. The tapered pins make local contact with the circumferential edge of the washer, and when the screw is rotated by a power tool connected to the fastening tool in a conventional manner, rotation of the washer in the tool is prevented by interference between the washer's peripheral edge and the bevelled pin surfaces.

In this way, with the washer retained against rotation, the screw is able to rapidly advance through the washer as the screw is turned during installation of the fastener assembly, for example, in the installation of insulation sheeting on a roof substructure. The installation tool is not limited in its uses to roofing constructions but may be used wherever a sheet material or sheeting, regardless of thickness and rigidity or flexibility, must be attached to a supporting structure.

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

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

Fig. 1 is an elevational view, in section, of an installation tool in accordance with the invention, holding a fastening element; and

Fig. 2 is a bottom view of the holding tool of Fig. 1 , with the fastener element removed.

With reference to the figures, the installation tool 10 in accordance with the invention includes a guide tube 12 connected to a receiver 14. Both are concentrically circular about an axis 16.

The receiver 14 includes a backing surface 18 that is slightly concave and surrounded by an annular collar 20 that tapers in the direction away from the guide tube 12. The collar terminates in an annular, generally planar face 22 that is used for pressing against an insulation layer during attachment of that layer to a substructure. Thus, a recess 34 with an expanded opening is provided.

The backing surface 18 is part of a back plate 24 having substantial thickness and rigidity. A central opening 26 in the back plate extends from the surface 18 and joins the central opening 28 of the guide tube 12. The opening 26 in the back plate 24 diverges, opening as it approaches the backing surface 18.

Three magnets 30 are symmetrically placed about the central axis 16, being embedded and held by adhesive in the back plate 24. A surface 32 of each magnet 30 is exposed in the recess 34 formed by the collar 20 and back plate 24. Also embedded in the collar 22 and backing surface 18, at the outer circumferential perimeter of the backing surface 18, are three short generally cylindrical pins 36. The exposed end 38 of the pin 36 is planar and generally parallel to the planar face 22 of the collar 20. The pins 36 are recessed within the collar 22 and have bevelled surface 40 that faces the central axis 16. The bevelled surface may be a flat or conica surface.

The three bevelled surfaces 40 together provide a tapered cradle, like a collet, that assists in centering a fastening element, as described hereinafter.

An imaginary radius 42 between the axis 16 and the center of the line 45 formed as an edge of the bevelled surface 43, meet at substantially a right angle 43. However, a deviation in either direction by an amount not exceeding approximately 15° is permissible and may be beneficial.

Use of three pins 36 provides stability when placing an object in the cradle formed by the bevelled surfaces 40. However, the quantity of pins is not limited to three and may be greater or less in number. Also, whereas three magnets 30 are illustrated, the quantity of magnets is not so limited; more or less magnets may be used. A single ring magnet (not shown}, concentric with the axis 16, may also be used and shapes, other than round, may also be used.

The installation tool, with the exception of the magnets and pins, is generally made of plastic that is hard and rigid. The pins are preferably of steel so that their surfaces 40 resist wear caused by interaction with the washer. The plastic elements of the tool may be fabricated by molding or casting. If the tool is made entirely of metal, the bevelled surfaces can be molded into the tool, and not be in the form of separate pins as described above.

When the guide tube and back plate, etc., are made as one piece of molded or cast plastic, the pins are held by using an adhesive in holes that are provided in the back plate. The magnets are also held by adhesive in holes provided in the back plate. Magnets serve no function and may be omitted when only plastic washers are to be used.

The installation tool 10 is used in conjunction with a fastener element 44 that includes a screw 46 and a washer 48 which engages the threaded portion 50 of the screw 46. The screw 46 also includes a drill tip 52 and a screw head 54. The screw head 54 has a thin integral flange 56 having a diameter that makes for a sliding fit in the central opening 28 of the guide tube 12. Such fastener elements 44 are delivered to the construction site in a preassembled condition with the washer attached at a fixed location on the screw so that all fastener elements are substantially similar. Because it is desired to have repeatability in operations when using these fastener elements, the central hub 58 of the washer is fabricated in a manner to provide a turn- resistant connection to the screw threads. Usually, a power tool is necessary if the screw 46 is to be advanced through the washer 48. Without application of sufficient force, the washer 48 will turn with the screw when the screw is rotated. How the hub 58 of the washer is fixed to the screw is not a novel portion of the present invention and accordingly is not described in detail herein.

When the screw head 54 and flange 56 are inserted in the guide tube 12 by way of the central opening 26 in the back plate 24, the circumferential edge 60 of the washer comes to rest on the bevelled surfaces 40 of the pins 36 that are fixedly mounted in the back plate 24, as described above.

The conical cradle formed by the multiple bevelled surfaces 40, centers the washer about the axis 16. This centering section is complemented by the centering provided by the flange 56 in the opening 28 of the guide tube 2. The diameter of the washer is such that the circumferential edge 60 will rest on the bevelled surfaces 40. Thus, a given installation tool 10 can accommodate washers of different diameters, but most preferably in a range so that the circumferential edge 60 is resting on the bevelled surfaces 40.

At this time, the washer 48, which is made of magnetically permeable material, e.g., steel, is close to the magnets 30. The washer is attracted by the magnet and held in place even though a gap may still exist between the washer 48 and the magnets 30. The illustrated washer has undulations which come close to the magnets. However, other contours for the washer, including a flat washer, may be used. The undulations in the washer provide stiffness which is advantageous in holding insulation layers on a substructure when external forces come into play, for example, walking on an insulated roof. The washer may also make direct contact with the magnets. When the washer 48 is attracted to the magnets 30, the installation tool 10 with a fastener element 44 in place (Fig. 1 } can be held with the drill end 52 pointing vertically downward, as illustrated, without the fastening element 44 separating from the installation tool 10.

in using the installation tool, a power driver (not shown) is inserted into the guide tube 12 through the end 62, and a socket on the end of the driver mates with the hex head of the screw head 54 and rotates the screw. The washer 48, however, does not rotate with the screw 46, because engagement of the circumferential edge 60 with the bevelled surfaces 40 prevents rotation of the washer 48 after the washer has seated in the cradle formed by the bevelled surfaces 40. Therefore, when rotated, the screw overcomes any resistant connection between the washer hub 58 and the threaded portion 50 of the screw, and the screw 46 advances through the washer until engagement is made by the drill tip 52 and threads 50 with the substructure to which attachment, for example, of an insulation layer, is to be made.

In this regard, the holding power of the pin surfaces 40 may be affected by the bevel angle 43 that is set between the imaginary radius 42 and the bevel edge 45. The bevel surfaces 40 tend to interfere more with the washer edge 60 when the angle 43 is not a right angle.

In such an installation, the combination of installation tool 0 and fastening element 44 is pressed against the outer surface of the insulation layer (not shown) so that the screw 46 penetrates until the planar face 22 of the installation tool 10 presses on the outer surface of the insulation layer. Then, rotation of the screw advances the screw while the washer is held stationary by the bevelled surfaces. The outer surface of the insulation layer is not damaged as the washer does not rotate.

Whereas, advantages of the magnets 30 in the installation tool 0 have been described above, it should be understood that in alternative embodiments in accordance with the invention, the magnets may be omitted whether steel or plastic washers are used.

Washers of cross sections other than that which has been illustrated, may be used. Basically, the tool 10 and fastener element 44 are constructed for use with each other within a particular range of washer diameters. The depth of the recess 34 in the back plate 24 may vary depending upon the washer that is intended for use therein, and it is not necessary that the washer 48 contact the backing surface when it is cradled on the bevelled surfaces 40. The backing surface limits deflection of the washer when the drill tip first presses into the insulation layer and first contacts the substructure.

Also, it should be understood that the washer need not be round. For non-round washers, the pins 36 and their bevelled surfaces 40 would be positioned, and the quantity of pins set, so that adequate support is provided in correspondence with the outline of the washer. For example, generally rectangular washers with rounded corners are frequently employed in the installation of insulation layers on a substructure. Further, the installation tool described above requires that the screw head 54 be inserted into the guide tube 12 through the central opening 26 in the backing surface 18. In installation tools of the prior art, it is also known to have a radial slot in the back plate 24 so that the screw can make a lateral entrance and position the screw head 54 and flange 56 within the central opening 28 of the tool 10. Pins with bevelled surfaces can be incorporated into tools having such radial entry and fall within the scope of the present invention.

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.

Claims

1 . An installation tool for use with a fastening element that includes a preassembled screw and washer, said screw having a threaded shank with a drill tip at one end and a screw head at the other end, said screw extending through a aperture of said washer and being substantially perpendicular to said washer, said washer having a peripheral edge surrounding said aperture, said installation tool comprising: a hollow guide tube having first and second ends and a longitudinal opening between said ends for receiving therein a screw head and at least a portion of said threaded shank of said preassembled screw; and segments of a generally conical surface which flares outwardly and away from said guide tube, said segments being connected to said guide tube and located at positions around said longitudinal opening, said segments of a generally conical surface together forming a cradle around said longitudinal opening for resting said peripheral edge of said washer thereon with said screw head and at least a portion of said screw shank in said hollow guide tube.

2. An installation tool as in claim 1 , further comprising magnet means connected to said guide tube for attracting washers of magnetic material and for urging said washers against said segments.

3. An installation tool as in claim 1 , further comprising a back plate connected to said guide tube with said longitudinal opening extended through said back plate, said segments being connected to and spaced from said back plate.

4. An installation tool as in claim 3, further comprising a collar surrounding at least a portion of an outer perimeter of said back plate, said collar extending away from said guide tube to form a recess for receiving said washer therein.

5. An installation tool as in claim 3, further comprising magnet means connected to said back plate for attracting a washer of magnetic material and urging said washer against said segments.

6. An installation tool as in claim 3, wherein each of said segments of a generally conical surface includes a cylindrical pin having a bevelled surface at one end, the other end being connected to said back plate.

7. An installation tool as in claim 5, wherein each of said segments of a generally conical surface includes a cylindrical pin having a bevelled surface at one end, the other end being connected to said back plate.

8. An installation tool as in claim 1 , wherein an angle between the center of said generally conical surface of each of said segments and a radius extending from the center of said longitudinal opening of said guide tube, is in a range of approximately 90° ± 5°.

9. An installation tool as in claim 3, wherein said back plate is circular and said segments lie in a concentric circle.

10. An installation tool as in claim 3, wherein a distance from said segments to said back plate prevents contact with said back plate of a washer resting on said segments.