Itw Limited

Utw Limited

George D Hewison

Robert H Day

A screw threaded method of making fastener particularly intended for use in fastening corrugated sheet material to metal purlins comprises a drilling point (1), a head (2), a first self-tapping screw threaded portion (3) adjacent the drilling point (1), a second screw threaded portion (4) adjacent the head (2), the second screw threaded portion (4) having a larger crest diameter than the first screw threaded portion (3), and an unthreaded portion (5) extending between the first and second screw threaded portions. The diameter of the part of the fastener carrying the second screw threaded portion (4) is generally larger than that carrying the first screw threaded portion 3 and the fastener also includes a transition portion (6) between its portions of smaller and larger diameter, and in particular, interposed between the trailing edge portion of the first screw threaded portion (3) and the leading edge portion of the unthreaded portion (5). The transition portion (6) includes forming portions (8 FIG. 4) projecting outwardly from the axis of the fastener no further than the diameter of the larger diameter portion. The forming portion (8) in use, enlarge the diameter of a hole drilled within the sheet material by mean of the drilling point (1) so as to allow passage of the larger diameter portion of the fastener through the sheet material. Such a fastener is formed by mean of a forward extrusion step which reduces its diameter and which, simultaneously, forms the forming portions (8) upon the transition (6) portion.

Method of forming a screw threaded fastener

It is known for colored plastics caps to be pushed by a customer onto heads of metal screws, after the screws have been secured to sheets of colored cladding or roofing. It is also known for the caps to be molded around the screw heads by a manufacturer. In the present invention, a screw/cap assembly is formed by bonding an initially separate cap onto the head of a screw by means of an adhesive, such as an epoxy resin sufficiently strong to allow the screw to be driven while the cap is in place. The intention is that the manufacturer would maintain stocks of the caps and stocks of the screws of different types, and only secure predetermined caps onto the heads of predetermined screws in response to specific orders from customers.

Screw/cap assemblies and their manufacture

A fastening assembly (1) for fastening a waterproof membrane and thick insulation to a roof deck comprises a screw threaded fastener (2) having a driving head (9), a clamp plate (5) for spreading the clamping load of the fastening assembly over an area of the surface of the waterproof membrane, a clamp tube (4) having a head (19& ) and a foot (18). The foot (18) is arranged to be engaged and held by the head (19) is arranged to engage and hold the clamp plate (5). An expanding auger (3) is formed between a screw thread (7) of the fastener (2) and the foot (18& ) of the clamp tube (4) In use, the auger (3) rotates with the fastener to expand the hole in the waterproof membrane through which the fastener (2) is inserted so that it accommodates the clamp tube (4) of the fastening assembly (1).

Fastening assembly

A screw threaded fastener particularly intended for use in fastening corrugated sheet material to metal purlins comprises a drilling point (1), a head (2), a first self-tapping screw threaded portion (3) adjacent the drilling point (1), a second screw threaded portion (4) adjacent the head (2), the second screw threaded portion (4) having a larger crest diameter than the first screw threaded portion (3), and an unthreaded portion (5) extending between the first and second screw threaded portions. The diameter of the part of the fastener carrying the second screw threaded portion (4) is generally larger than that carrying the first screw threaded portion (3) and the fastener also includes a transition portion (6) between its portions of smaller and larger diameter and in particular, interposed between the trailing edge portion of the first screw threaded portion (3) and the leading edge portion of the unthreaded portion (5). The transition portion (6) includes forming portions (8) projecting outwardly from the axis of the fastener no further than the diameter of the larger diameter portion. The forming portions (8) in use, enlarge the diameter of a hole drilled within the sheet material by means of the drilling point (1) so as to allow passage of the larger diameter portion of the fastener through the sheet material. Such a fastener is formed by means of a forward extrusion step which reduces its diameter and which, simultaneously, forms the forming portions (8) upon the transition portion (6).

Screw threaded fastener

A fastening assembly for use in fastening a thick insulating layer 8, typically between 130 and 300 mm, onto a roof decking 9 comprises a self drilling and self tapping screw-threaded fastener 1 having a driving head 11; a load distributing plate 2 for engaging the upper surface of the insulation material 8 to hold it and distribute the fastening load so that the fastening assembly does not pull through the insulation material; and, an extensible resilient member 3 having one end 6 coupled to the head of the screw-threaded fastener 1 and the other end coupled to the load distributing plate 2. At least one coupling permit the screw-threaded fastener 1 to rotate with respect to the load distributing plate 2 to allow the fastener 1 to be driven through and screwed into the roof decking 9 to fasten the insulation material 8. The provision of a resilient element 3 accommodates minor variations in the manufacture of the insulation material, and distortions and deformations of it that occur in use. The resilient element 3 also accommodates any lateral movement of the load-distributing plate and the screw-threaded fastener caused by, for example, thermal expansion and contraction or settlement of the building.

An adjustable control assembly comprises first abutment means such as a U-shaped foot for placement against a workpiece, the first abutment means being provided on first spacing means such as a rod which is movable with respect to second abutment means such as a nut-like member, the second abutment means being provided on second spacing means such as a hollow tube which is movable with respect to third abutment means such as a combined pinch bracket and locator tube for attachment to a worktool, the preset distance between the first and third abutment means being adjustable to correspond to the desired initial position of the worktool with respect to the workpiece, and the preset distance between the second and third abutment means being adjustable to correspond to the maximum permitted advance of the worktool with respect to the workpiece, the preferred application of the adjustable control assembly being in the use of a rotary power tool to secure, to roof decking, a fastening assembly including an extensible resilient element passing through compressible insulation material.

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Twyford, United Kingdom

George D Hewison