GB2181087A

GB2181087A - Nail fixing device

Info

Publication number: GB2181087A
Application number: GB08623401A
Authority: GB
Inventors: Brian William Edwards; Clive Watson Gibson
Original assignee: British Telecommunications PLC
Current assignee: British Telecommunications PLC
Priority date: 1985-09-30
Filing date: 1986-09-29
Publication date: 1987-04-15
Also published as: GB8623401D0; GB8524021D0

Abstract

A hand held sleeve (14) supports a punch (10). A pin is secured to the punch at one end and the punch is struck at its opposite butt end. Once the pin is in place a bush (24) is rotated to apply a predetermined force to the punch to test the load capacity of the pin. The force is determined by the stiffness of spring washers 36 and the degree of movement of bush 24. <IMAGE>

Description

SPECIFICATION Nail fixing device This invention relates to hand-held tools, for driving anchoring pins into a receiving material, of the type comprising a tubular sleeve and a punch slideably guided in said sleeve. As used herein "anchoring pin" includes similar anchoring means such as nails and studs etc. The receiving material may be concrete, brick, stone, wood, masonary or steel etc.

Tools of the aforementioned type have been known and used for some time; an example is shown in United States Patent No 2488279.

Further developments have provided, for example, tools with adjustable support means as shown in French Patent No 1136523.

The aforesaid tools are used for installing, amongst other things, telephone cables, data cables, power cables, piping and conduit. The installation of a telephone cable, for example, may require many anchoring pins to be used in many different receiving materials. It is therefore important that the anchoring pins are not too large, so as to minimise unit cost and minimise damage to the receiving material, while providing a secure fixing. The installation cost may be reduced by using smaller pins but any saving made will be lost several times over if fixings fail at different times and then have to be individually repaired.

A known technique of ensuring that a nail is secured firmly is to apply a predetermined force to the nail in an attempt to remove the nail from its fixed position. If the nail is removed then a larger nail is secured into the hole previously formed by the original nail. A problem with this technique is that three tools are required-a hammer, a fixing device (for holding the nail) and a testing device. In practice this often leads to the testing step being ignored resulting in unsatisfactory nails being left to support the load.

According to the present invention there is provided a hand-held fixing tool comprising a tubular sleeve and a punch slideably guided in said sleeve arranged to drive an anchoring pin into a receiving material: characterised in that the anchoring pin is secured to the punch, and the tool further comprises loading means for applying a predetermined force on the punch after the anchoring pin has been driven into the receiving material to test the load capacity of the anchoring pin.

In a preferred embodiment the load applying means comprises a bush threaded onto the punch which applies a force on the punch against the sleeve via a spring. Preferably the load applied to the nail is determined by measuring the displacement of the bush relative to the sleeve. Preferably the punch includes a tapped hole for receiving a threaded anchoring pin.

The anchoring pin may be driven into the receiving material by an explosive charge but in a preferred embodiment the punch includes a butt extending from the sleeve which is struck by a hammer to drive the anchoring pin into the receiving material.

The invention will now be described, by way of example only, with reference to the accompanying figure which shows a cross section through the central axis of a hand held fixing tool.

Force is transmitted from a hammer to an anchoring pin via a punch 10 which, at its hammer end, has a butt 12. The punch 10 is free to slide within a sleeve 14 the exterior of which is designed to be hand-held while the butt 12 is struck. At its wall end the sleeve has a wall plate 16, perpendicular to the axis of the device, the exterior surface of which is placed against the receiving material into which an anchoring pin is to be secured. The wall plate 16 has a central hole 18 and the pin end of the punch 10 has a cylindrical end section 20 which is small enough to enter hole 18. The length of-section 20 is less than the thickness of wall plate 16 and the remainder of the punch 10 has a larger diameter than hole 18 so that the punch 10 cannot extend beyond the external surface of plate 16.

Adjacent to section 20 the punch 10 has a tapped section 22 onto which is threaded a withdrawal-bush 24. Between threaded section 22 and but 12 the punch 10 has a shaft 26 and the bush 24 has a non-threaded section 28 which extends over shaft 26 beyond the hammer end of the sleeve 14. At the hammer end of the sleeve 14 a back plate 30, perpendicular to the axis of the device, has a central hole 32 which firmly supports bush 28-the gap being exaggerated in the figure. The diameter of the wall end of section 28 increases so that the bush 24 is restrained by plate 30.

The hammer end of the bush 28 terminates before the butt 12 is reached so that rod 10 extends out of, but is held firmly by, the bush. At the hammer end of the bush 28 a pair of torque-rods 34 extend perpendicular to the axis of the device.

Between the internal surface of plate 16 and the wall end of bush 24 are positioned six spring washers 36 which encircle a threaded portion of the punch rod 10. Washers 36 are of a predetermined stiffness thus allowing a direct measurement of displacement to be interpreted as force applied to an anchoring pin.

To insert and test an anchoring pin the device is held with the hammer end uppermost, the bush 24 is restrained with respect to sleeve 14 by the torque rods 34 and the punch 10 is screwed clockwise-working downwards. The wall end surface of the bush 24 is thereby screwed away from the internal surface of plate 16 and no force is applied to springs 36.

The bush 24 is free to slide along the axis of the tool while carrying the punch 10 with it. When the threaded section of the punch 10 is against plate 16 this is the "in" position and when the raised portion of bush 24 is against plate 30 this is the "out" position.

The device is now placed in the "in" position and a pin 28 is screwed into the thread in the punch 10. The bush is now pulled into the "out" position-the pin 38 may have a support ring along its shaft which holds it firmly within the support collar. Plate 16 is placed against a wall 40 and the butt 12 is struck with a hammer until the "in" position is reached thus driving the pin into the wall.

The bush 24 is now screwed clockwise, relative to both the punch 10 and the sleeve 14 thus compressing springs 36. If the nail remains firmly in position then the sleeve 14 and the punch 10 will remain stationary but the bush 24 will move towards the wall end and exert a force on the punch. This force is proportional to the displacement of the bush 24 relative to the sleeve 14 and said force may be determined by placing coloured bands on the bush 24. A coloured band on the bush 24 becoming totally obscured by the support collar may signify that the anchoring pin 38 will support the required load.

Claims

1. A hand-held fixing tool comprising a tubular sleeve (14) and a punch (10) slideably guided in said sleeve arranged to drive an anchoring pin (38) into a receiving material: characterised in that the anchoring pin is secured to the punch, and the tool further comprises loading means (26, 36) for applying a predetermined force on the punch after the anchoring pin has been driven into the receiving material to test the load capacity of the anchoring pin.

2. A fixing tool according to claim 1 in which the load applying means comprises a bush (24) threaded onto the punch which applies a force on the punch against the sleeve via a spring (36).

3. A fixing tool according to claim 2 in which the load applied to the nail is determined by measuring the displacement of the bush relative to the sleeve.

4. A fixing tool according to any preceding claim in which the punch includes a tapped hole for receiving a threaded anchoring pin.

5. A fixing tool according to any preceding claim in which the punch includes a butt (12) extending from the sleeve which is struck by a hammer to drive the anchoring pin into the receiving material.

6. A nail fixing device substantially as herein described with reference to the accompanying drawing.