GB2181204A

GB2181204A - Screw retention means

Info

Publication number: GB2181204A
Application number: GB08620663A
Authority: GB
Inventors: Graham Shute; Michael Arthur Wood
Original assignee: Linolite Ltd
Current assignee: Linolite Ltd
Priority date: 1985-09-11
Filing date: 1986-08-26
Publication date: 1987-04-15
Also published as: GB8620663D0

Abstract

A sheet of material 1 to be secured to a support has through it an aperture 2 with three slots 3 extending outwardly from it. The aperture 2 has a diameter which will allow passage through it of the shaft 4 of a screw but which will prevent passage of the screw head 5. End faces 3A of each slot 3 continue upwardly from the sheet 1 in a stem 6 which terminates at its upper end in a head 7. The head 7 has an inwardly-inclined upper face 8 and downwardly-facing shoulder 9 which extends over the slot 3. The stem is resilient. In use, the screw is pressed downwards into the aperture 2 so that the screw head 5 engages the inclined upper face 8 of the head 7 so forcing the head 7 radially outwardly by bending the stem 6, to allow the head of the screw to pass. When it has done so, the resilient stem 6 returns to its original position, bringing the head 7 over the screw so that the screw is captive in the aperture 2. <IMAGE>

Description

SPECIFICATION Screw retention means This invention relates to means for retaining a screwthreaded member.

Very many products are sold forfitmentto structures in a house or factory by means of screwthreaded members such as screw nails or bolts, and in many cases the products are to befitted in such an attitude that the screws are inserted at an upward angle. This can often result in the screws falling out oftheirintended holes and being lost. As well asthe inevitable frustration caused to the operator, serious repercussions can ensue, as the operator may fail to replace the screw and thereby leave the product incompletely secured.

It has previously been proposed to provide a cap tivescrewwhich is undercuttofitwithin a prepared hole, the head and shaft of the screw both being of greater diameterthan the hole; however, such screws can only be inserted by deforming the material around the hole, and the material may notfully return to its original form; the screw can then escape.

It has also been proposed to provide a resilient plastics sleeve around the shaft ofthe screw, but this can become trapped between the product and the structure to which it is being screwed and thereby prevent flush fitting.

According to the present invention there is provided means for retaining a screw-threaded member, comprising an aperture in material to be secured by the screw-threaded member and having a diameter greater than that of the member's shaft but less than that of the member's head,the screw-threaded member's shaft extending through the aperture, and retention means extending from the material adjacent the aperture and having an abutment face directed towards the material and spaced from the material by a distance equal to or greater than the depth of the member's head,the abutment face extending over the member's head to prevent retraction of the head past the abutment face.

The abutmentface is preferablyspacedabovethe material by a distance less than the length ofthe shaft ofthescrew-threaded member so asto preventthe member leaving the aperture.

Preferably the retention means comprises one or more upstanding legs having abutment faces in the form of downwardly-directed shoulders. The legs may be spaced around the periphery ofthe aperture, and may be formed from the material to be secured.

The retention means is preferably resilient so that on insertion into the aperture the head of the screwthreaded member can force the retention means outwardly to allow it to pass, after which the retention means springs back into its initial position in which the abutment face extends over the head ofthe member.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa plan view of means for retaining a screw-threaded member, in accordance with the invention; and Figure2 is a sectional side view of a portion ofthe means of Figure 1.

Referring to the drawings, a plate-like sheet of material 1 is to be secured to a support; in the present case the sheet 1 may form a backplate for a luminaire which is to be screwed to a ceiling, and the backplate is a plastics moulding.

The backplate 1 is moulded with an aperture through it, the aperture having a central circular por tion 2withthree equispaced slots3extending radially outwardly from it. The circular aperture 2 has a diameter which will allow passage through it ofthe shaft 4 of a screw (Figure 2) but which will prevent passage of the screw head 5. The head 5 of the screw has a diameter slightly less than the circle defined by the end faces 3A of the slots 3.

The end faces 3A each continue upwardlyfrom the plate 1 in a stem 6 which terminates at its upper end in a head 7. The stem 6 and head 7 are formed during the moulding of the backplate 1 by means of a portion of the mould passing upwardly through the slot 3 and forming the underside of the head 7.

The head 7 has a n i an inwardly-inclined upper face 8 and downwardly-facing shoulder 9 which extends overtheslot3.Thestem6 is resilient.

In use, the plate 1 isto be secured to a ceiling,and screws are provided for each of the apertures 2. During packing of the plate 1 for sale each screw is pressed into a central aperture 2 so that the screw head 5 engages the inclined upper face 8 of the head 7, which forces the head 7 radially outwardly, bending the stem 6, to allow the head ofthe screw to pass. When it has done so, the resilient stem 6 returns to its original position, bringing the head 7 over the screw so thattheshoulder9 prevents retraction of the screw from the aperture 2.

When the plate is to be fitted to the ceiling, therefore,the shoulder 9 prevents the screwfrom falling out but is spaced from the plate 1 by a greaterdis trance than the depth ofthe screw head 5; the screw head can therefore rotate between the shoulder9 and the plate 1 for driving the screw into the ceiling.

This embodiment of the invention allows the plate to be secured to a ceiling without the risk of losing the fixing screws which, once inserted into the aperture, are permanently retained therein without interference with their insertion into or retraction from the ceiling. A screwdriver easily fits between the heads 7 ofthe retaining means.

Modifications and improvements may be made without departing from the scope of the invention.

1. Meansforretaining ascrew-threaded member, comprising an aperture in material to be secured by the screw-threaded member and having a diameter greater than that of the member's shaft but less than that of the member's head, the screwthreaded member's shaft extending through the aperture, and retention means extending from the material adjacent the aperture and having an abutment face directed towards the material and spaced from the material by a distance equal to or greater than the depth of the member's head,theabutment

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Screw retention means This invention relates to means for retaining a screwthreaded member. Very many products are sold forfitmentto structures in a house or factory by means of screwthreaded members such as screw nails or bolts, and in many cases the products are to befitted in such an attitude that the screws are inserted at an upward angle. This can often result in the screws falling out oftheirintended holes and being lost. As well asthe inevitable frustration caused to the operator, serious repercussions can ensue, as the operator may fail to replace the screw and thereby leave the product incompletely secured. It has previously been proposed to provide a cap tivescrewwhich is undercuttofitwithin a prepared hole, the head and shaft of the screw both being of greater diameterthan the hole; however, such screws can only be inserted by deforming the material around the hole, and the material may notfully return to its original form; the screw can then escape. It has also been proposed to provide a resilient plastics sleeve around the shaft ofthe screw, but this can become trapped between the product and the structure to which it is being screwed and thereby prevent flush fitting. According to the present invention there is provided means for retaining a screw-threaded member, comprising an aperture in material to be secured by the screw-threaded member and having a diameter greater than that of the member's shaft but less than that of the member's head,the screw-threaded member's shaft extending through the aperture, and retention means extending from the material adjacent the aperture and having an abutment face directed towards the material and spaced from the material by a distance equal to or greater than the depth of the member's head,the abutment face extending over the member's head to prevent retraction of the head past the abutment face. The abutmentface is preferablyspacedabovethe material by a distance less than the length ofthe shaft ofthescrew-threaded member so asto preventthe member leaving the aperture. Preferably the retention means comprises one or more upstanding legs having abutment faces in the form of downwardly-directed shoulders. The legs may be spaced around the periphery ofthe aperture, and may be formed from the material to be secured. The retention means is preferably resilient so that on insertion into the aperture the head of the screwthreaded member can force the retention means outwardly to allow it to pass, after which the retention means springs back into its initial position in which the abutment face extends over the head ofthe member. An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa plan view of means for retaining a screw-threaded member, in accordance with the invention; and Figure2 is a sectional side view of a portion ofthe means of Figure 1. Referring to the drawings, a plate-like sheet of material 1 is to be secured to a support; in the present case the sheet 1 may form a backplate for a luminaire which is to be screwed to a ceiling, and the backplate is a plastics moulding. The backplate 1 is moulded with an aperture through it, the aperture having a central circular por tion 2withthree equispaced slots3extending radially outwardly from it. The circular aperture 2 has a diameter which will allow passage through it ofthe shaft 4 of a screw (Figure 2) but which will prevent passage of the screw head 5. The head 5 of the screw has a diameter slightly less than the circle defined by the end faces 3A of the slots 3. The end faces 3A each continue upwardlyfrom the plate 1 in a stem 6 which terminates at its upper end in a head 7. The stem 6 and head 7 are formed during the moulding of the backplate 1 by means of a portion of the mould passing upwardly through the slot 3 and forming the underside of the head 7. The head 7 has a n i an inwardly-inclined upper face 8 and downwardly-facing shoulder 9 which extends overtheslot3.Thestem6 is resilient. In use, the plate 1 isto be secured to a ceiling,and screws are provided for each of the apertures 2. During packing of the plate 1 for sale each screw is pressed into a central aperture 2 so that the screw head 5 engages the inclined upper face 8 of the head 7, which forces the head 7 radially outwardly, bending the stem 6, to allow the head ofthe screw to pass. When it has done so, the resilient stem 6 returns to its original position, bringing the head 7 over the screw so thattheshoulder9 prevents retraction of the screw from the aperture 2. When the plate is to be fitted to the ceiling, therefore,the shoulder 9 prevents the screwfrom falling out but is spaced from the plate 1 by a greaterdis trance than the depth ofthe screw head 5; the screw head can therefore rotate between the shoulder9 and the plate 1 for driving the screw into the ceiling. This embodiment of the invention allows the plate to be secured to a ceiling without the risk of losing the fixing screws which, once inserted into the aperture, are permanently retained therein without interference with their insertion into or retraction from the ceiling. A screwdriver easily fits between the heads 7 ofthe retaining means. Modifications and improvements may be made without departing from the scope of the invention. CLAIMS

1. Meansforretaining ascrew-threaded member, comprising an aperture in material to be secured by the screw-threaded member and having a diameter greater than that of the member's shaft but less than that of the member's head, the screwthreaded member's shaft extending through the aperture, and retention means extending from the material adjacent the aperture and having an abutment face directed towards the material and spaced from the material by a distance equal to or greater than the depth of the member's head,theabutment face extending over the member's head to prevent retraction ofthe head past the abutment face.

2. Means for retaining a screw threaded member as claimed in Claim 1, wherein the abutment face is spaced above the material bya distance lessthanthe length of the shaft of the screw-threaded member.

3. Means for retaining a screw threaded member as claimed in Claim 1 or Claim 2, wherein the retention means comprises an upstanding leg having an abutment face in the form of a downwardly-directed shoulder.

4. Means for retaining a screw threaded member as claimed in Claim 3, wherein a pluralityofupstand- ing legs are provided spaced around the periphery of the aperture.

5. Means for retaining a screw threaded member as claimed in any one of the preceding Claims, wherein the retention means is resiliently biassed overthe aperture.

6. Means for retaining a screw threaded member substantially as hereinbefore described with refer ence to the accompanying drawing.