GB2268241A - Fastener having recessed,non-circular head - Google Patents

Abstract

A screw 20 has a non-circular head (22) with a concave recess (40) for aligning the head (22) relative to a non-circular drive socket (108) of a driving tool (56), the recess (40) having six triangular walls (46) defining an upper, polygonal edge (162). <IMAGE>

Description

FASTENER RAVING RECE88ED, NON-CIRCULAR HEAD This invention pertains to an improved fastener having a non-circular or polygonal head and having a shank with a threaded portion, such as a screw having a hexagonal head and having a shank with a threaded portion and with a drilling tip. This invention provides an improved way to center a non-circular socket of a fastener-driving tool and the non-circular head relative to each other at the start of the driving operation.

So-called stand-up screw guns, which are powered by trigger-actuated, electric motors, are exemplified in Murray U.S. Patent No. 3,960,191, Dewey U.S. Patent No.

4,236,555, and Dewey U.S. Patent No. 4,397,412 and are available commercially from ITW-Buildex (a unit of Illinois Tool Works Inc.) of Itasca, Illinois, under its AUTOTRAXX trademark.

Typically, stand-up screw guns employ driving members with driving tips, such as driving tips adapted to drive Phillips-head screws. Fastener-driving tools of other types, which may be powered by electric motors or by pneumatic motors, employ driving members with driving sockets, which fit axially over conforming heads of fasteners, such as screws or bolts. Typically, the sockets and fastener heads are non-circular or polygonal when viewed axially. Commonly, the sockets and fastener heads are hexagonal when viewed axially.

Often, it is difficult for a user to center the noncircular socket of such a tool and the non-circular head of such a fastener, particularly if a stand-up screw gun is used. Although a bolt or machine screw can be manually started for a few turns into a pre-threaded hole in a workpiece, it is difficult for a user to stabilize a screw having a non-circular head and having a drilling or tapping tip before the screw has been driven for a few turns into a workpiece. Centering of the non-circular socket of a fastener-driving tool and the non-circular head of such a screw, therefore, can be especially difficult for a user.

If the non-circular socket of such a fastener-driving tool and the non-circular head of such a fastener are not centered relative to each other, it is possible for the fastener, the workpiece, or both to be damaged if an attempt is made to drive the fastener into the workpiece via the fastener-driving tool. The non-circular socket may be damaged also.

Therefore, there has been a need, to which this invention is addressed, for an improved way to center the non-circular socket of such a fastener-driving tool and the non-circular head of such a fastener relative to each other.

According to a first aspect of this invention a fastener having an axis comprises the fastener having a head and a shank having a threaded portion, the head being non-circular when viewed axially so as to adapt the head to co-act with a driving member having a socket shape so that the socket can be axially fitted over the head, wherein the head has a recess extending axially into the head and defining a continuous, upper edge conforming to the shape of a regular polygon, the concave recess having a plurality of substantially triangular surfaces, which are arranged in a regular array about the axis of the fastener which provides a datum useful in centering such a socket and the head relative to each other and adapting the fastener to co-act with a centering pin associated with such a driving member.

This invention facilitates centering of the noncircular socket of a tool and the non-circular head of the improved fastener relative to each other via a centering pin of the driver co-acting with a concave recess in the non-circular head of the fastener.

The improved fastener has a shank which may be fully threaded or may be alternatively provided with a drilling or tapping tip. It is preferred for the shank to have a drilling tip. The head is non-circular, preferably hexagonal, when viewed axially, so as to adapt the head to co-act with a driving member having a suitably shaped socket in a fastener driving tool, such as a stand-up screw gun or a hand held screw gun. The head is adapted, therefore, to co-act with the non-circular socket of the driving member of the tool.

The concave recess is distinguished from a slotted, cross-shaped, or other recess designed to receive a screwdriver blade. The concave recess provides a datum useful in centering the non-circular socket of the driving member of a fastener driving tool, and the non-circular head of the improved fastener relative to each other. Moreover, as explained below, the concave recess adapts the fastener to co-act with a centering pin associated with such a driving member.

Preferably, the concave recess has six such surfaces defining a continuous, upper edge conforming to a regular hexagon.

Particular embodiments of fasteners in accordance with this invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a fragmentary, exploded view of some components of a stand-up screw gun, along with a screw constituting a preferred embodiment of the improved fastener; Figure 2 is an enlarged, fragmentary, elevational detail of a modified socket co-acting with the screw shown in Figure 1; and, Figure 3 is an enlarged, fragmentary, perspective detail of a centering pin having a convex end, along with a screw according to the present invention.

The screw 20 is similar to the screw disclosed in Sygnator U.S. Patent No. 4,583,898.

Thus, the screw 20, which has an axis, has a head 22, a shank 24, and a washer-like portion 26 between the head 22 and the shank 24. The head 22 is hexagonal when viewed axially, so as to adapt the head 22 to co-act with a suitably shaped socket of a fastener driving tool, such as the socket of the screw gun as described in our co-pending Application No. GB-A-2,250,559. The shank 24 has a threaded portion 28 adjoining the washer-like portion 26 and a drilling tip 30 adjoining the threaded portion 28.

Details of a drilling tip like the drilling tip 30 are found in the Sygnator patent noted above.

The screw 20 differs from the screw disclosed in the Sygnator patent noted above, and from other fasteners known heretofore, in having a concave recess 40 extending axially into the head 22, from a top surface 42 of the head 22.

The concave recess 40 provides a datum that is useful in centering a socket of a fastener-driving tool, such as the screw gun described in GB-A-2,250,559, and the screw head 22 relative to each other before the fastener-driving tool is used to drive the screw 20.

As shown in Figure 3, the concave recess 40 in the head 22 of the screw 20 has six substantially triangular surfaces 160, which are arranged in a regular array about the axis of the screw 20. Such surfaces 160 define a continuous, upper edge 162, which conforms to a regular hexagon having each of six respective sides parallel to an adjacent one of six flat surfaces 164 of the screw head 22.

When fixing the screw, a fastener-driving tool is used which has a non-circular or polygonal socket for driving the fastener. The socket also includes a centering pin 120.

The centering pin 120 is hexagonal in cross section.

The centering pin 120 rotates conjointly with the socket, which is hexagonal when viewed axially. The centering pin 120 and the socket are oriented similarly in a rotational sense, whereby each of six axially extending, flat surfaces 166 defined by the centering pin 120 is parallel to an adjacent one of six flat surfaces 168 defined by the socket in the tubular extension 108.

The convex end 122 of the centering pin 120 conforms generally to the concave recess 40 in the head 22 of the screw 20 and has six substantially triangular facets 170 arranged in a regular array about the axis of the centering pin 120. The facets 170 converge toward the axis of the centering pin 120 and conform substantially to a pyramid having a regular, hexagonal base. The convex end 122 has a small, blunt tip 172.

Because the centering pin 120 rotates conjointly with the socket 110, the centering pin 120 orients the screw 20 in such manner that the socket 110 and the head 22 of the screw 20 are oriented similarly in a rotational sense, when the convex end 122 of the centering pin 120 is fitted axially into the concave recess 40 in the head 22 of the screw 20. Thus, when the socket and the screw head 122 are oriented similarly in a rotational sense as well as centered relative to each other, the socket 110 can be axially fitted over the screw head 22 without interference.

Claims (5)

1. A fastener having an axis, the fastener having a head and a shank having a threaded portion, the head being noncircular when viewed axially so as to adapt the head to coact with a driving member having a socket shape so that the socket can be axially fitted over the head, wherein the head has a recess extending axially into the head and defining a continuous, upper edge conforming to the shape of a regular polygon, the concave recess having a plurality of substantially triangular surfaces, which are arranged in a regular array about the axis of the fastener which provides a datum useful in centering such a socket and the head relative to each other and adapting the fastener to co-act with a centering pin associated with such a driving member.

2. A fastener according to claim 1, wherein the concave recess has six said walls defining a continuous, upper edge conforming to a regular hexagon.

3. A fastener according to any one of the preceding claims, wherein the head is hexagonal when viewed axially.

4. A fastener according to any one of the preceding claims, wherein the shank has a drilling-tip.

5. A fastener substantially as described with reference to the accompanying drawings.