GB1573624A

GB1573624A - Metal push-on fasteners

Info

Publication number: GB1573624A
Application number: GB112276A
Authority: GB
Original assignee: Baker and Finnemore Ltd
Current assignee: Baker and Finnemore Ltd
Priority date: 1976-01-13
Filing date: 1976-01-13
Publication date: 1980-08-28
Also published as: IT1058656B; FR2338411A1; FR2338411B3

Description

(54) IMPROVEMENTS IN METAL PUSH-ON FASTENERS (71) We, BAKER & FINNEMORE LIMITED, a British Company of 199 Newhall Street, Birmingham B3 1SN do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to sheet metal push-on fasteners for gripping smooth cylindrical shanks. "Shanks" is used to refer collectively to cylindrical surfaces such as spindles and shafts, and the shanks of studs and pins.In one example of the type of push-on fastener with which the present invention is concerned, the fastener is generally flat and made of spring steel and has continuous outer portion at the back of which is a bearing surface to engage an article to be retained and an inner portion having locking fingers extending radially inwards towards a circular aperture for receiving a cylindrical shank which the fingers are to grip, the locking fingers diverging forwards from the plane of the bearing surface and having arcuate tips which, when the fastener is pushed along the shank in the direction in which the locking fingers trail, slide over the surface but when pushed in the opposite direction grip the shank and resist relative movement.

Such push-on fasteners suffer from the disadvantage that on being fitted to a shank they can be left in an attitude in which the bearing surface at the back of the retainer is, in the example cited, oblique to the axis of the shank so making only point contact with the article.

Push-on fasteners of top hat shape are known which are better in this respect. These fit over the end of a shank and comprise a sleeve closed at one end and having an annular flange extending radially at the other.

Gripping fingers slit from the sleeve but remaining integral with the flange are inclined inwards at a small acute angle to the sleeve. The sleeve fairly closely surrounds the shank which is gripped by the fingers.

The flange forms a bearing surface to engage an article to be retained on the shank and is held substantially at right angles to the shank axis by the close fit of the sleeve and the small angle which the fingers make with the shank surface. Because of this small angle however the gripping fingers do not resist removal of the fastener from the shank as well as locking fingers of the flat fasteners which are at a much larger acute angle to the shank. The closed end of the top-hat fasteners prevents its use other than over the end of a shank unless the closed end is removed but this weakens the fastener excessively.

As a cover over the end of the shank a top hat fastener, because of its shape and the broken outline due to the pierced fingers, is less attractive in appearance than at flat fastener fitted with a domed cap.

The present invention consists in a sheet metal push-on fastener for gripping a smooth cylindrical shank, the fastener comprising an inner portion defining an aperture for receiving a cylindrical shank, and a continuous outer portion surrounding the inner portion, the inner portion comprising fingers all having their tips at the aperture, some of the fingers being locking fingers and others stabilising fingers interposed between the locking fingers, the locking fingers being inclined with respect to the axis of the aperture, and having arcuate edges at their tips, and the stabilising fingers having extended tips which are confined to the same side of the fastener as the locking fingers, the arrangement being such that, in use of the fastener, the fingers engage the cylindrical surface of a shank of predetermined size entered in the aperture and the locking fingers lie oblique to the said surface of the shank, and when the fastener is pushed along the shank in the direction in which the locking fingers trail their arcuate edges slide along the shank but when pushed in the opposite direction they grip the shank and resist relative movement, and the extended tips of the stabilising fingers embrace an axial extent of the shank so as to urge the fastener to remain in a predetermined attitude with respect to the axis of the shank, but such as not to resist relative movement when the fastener is pushed along the shank in said opposite direction.

The tips of the stabilising fingers may have any of a variety of forms shaped to engage stably an axially extensive portion of the shank but may conveniently be of tapering part-cylindrical shape. As they make contact with the shank over a length instead of in one transverse plane or the shank, the stabilising fingers co-operate to ensure that the fastener can be fitted to the shank in the required attitude. The locking fingers perform their normal function of securing the fastener on the shank.

The stabilising fingers are preferably spaced equi-angularly about the aperture and so are the locking fingers. The stabilising fingers may be alternated with the locking fingers. The fingers may be separated from one another by slits or by narrow slots. The closed ends of the slits or slots are preferably rounded to avoid incipient cracks. Slits may be rounded by terminating in circular holes pierced through the metal.

The accompanying drawings shown one form of fastener according to the invention.

In the drawings: Figure 1 is a plan view of the fastener, Figure 2 is a cross-section on line 2-2 of Figure 1 and Figure 3 is a cross-section on line 3-3 of Figure 1.

The fastener is formed from spring steel sheet and has a continuous annular outer portion 3, with a peripheral flange 4, and an inner portion 5 divided into two locking finger 6 and two stabilising fingers 7 extending radially inwards towards an aperture 8 and separated by narrow slots 9 the closed ends of which are rounded. The two locking fingers 6 are diametrically opposite to one another and so are the two stabilising fingers 7 so that locking fingers and stabilising fingers alternate. The locking fingers 6 subtend a smaller angle at the centre of the aperture 8 than the stabilising fingers 7 and any grain of the spring steel runs parallel to the line 2-2.

The back of the outer portion 3 forms a bearing surface 10. The locking fingers 6 from their roots at the Junction between the inner and outer portion 3 and 5 are inclined forwards from the plane of the bearing surface and have arcuate tips. The main parts of the stabilising fingers 7 remain in the plane of the bearing surface 10 as far as the aperture 8 but have extended tips 11 bent forwards and of tapering part-cylindrical shape.

When, as indicated in Figure 2, the back of the fastener is over the end of a shank 12, the locking fingers 6 and stabilising fingers 7 yield to allow the shank to enter the aperture 8. The stabilising fingers 7 guide the fastener and keep its bearing surface at right angles to the shank axis. The locking fingers 6 resist withdrawal of the fastener in the opposite direction. The fastener may be fitted, as also indicated in Figure 2, with a domed cap 13 the free edge of which is closed over the back edge of the flange 4.

WHAT WE CLAIM IS: 1. A sheet metal push-on fastener for gripping a smooth cylindrical shank, the fastener comprising an inner portion defining an aperture for receiving a cylindrical shank, and a continuous outer portion surrounding the inner portion, the inner portion comprising fingers all having their tips at the aperture, some of the fingers being locking fingers and others stabilising fingers interposed between the locking fingers, the locking fingers being inclined with respect to the axis of the aperture, and having arcuate edges at their tips, and the stabilising fingers having extended tips which are confined to the same side of the fastener as the locking fingers, the arrangement being such that, in use of the fastener, the fingers engage the cylindrical surface of a shank of predetermined size entered in the aperture and the locking fingers lie oblique to the said surface of the shank, and when the fastener is pushed along the shank in the direction in which the locking fingers trail their arcuate edges slide along the shank but when pushed in the opposite direction they grip the shank and resist relative movement, and the extended tips of the stabilising fingers embrace an axial extent of the shank so as to urge the fastener to remain in a predetermined attitude with respect to the axis of the shank, but such as not to resist relative movement when the fastener is pushed along the shank in said opposite direction.

2. A sheet metal push-on fastener as claimed in claim 1 wherein the outer portion defines a planar bearing surface to engage an article to be retained on the shank and the fingers are arranged so that in use of the fastener the bearing surface is held at right angles to the axis of the shank.

3. A sheet metal push-on fastener as claimed in claim 2 wherein main portions of the stabilising fingers remain in the plane of the bearing surface as far as the aperture and the extended tip of each stabilising finger is at right angles to the main portions thereof.

4. A fastener as claimed in any preceding claim wherein the extended tips of the stabilising fingers are of tapering partcylindrical shape.

5. A fastener as claimed in any preceding claim having one opposed pair of locking

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. along the shank but when pushed in the opposite direction they grip the shank and resist relative movement, and the extended tips of the stabilising fingers embrace an axial extent of the shank so as to urge the fastener to remain in a predetermined attitude with respect to the axis of the shank, but such as not to resist relative movement when the fastener is pushed along the shank in said opposite direction. The tips of the stabilising fingers may have any of a variety of forms shaped to engage stably an axially extensive portion of the shank but may conveniently be of tapering part-cylindrical shape. As they make contact with the shank over a length instead of in one transverse plane or the shank, the stabilising fingers co-operate to ensure that the fastener can be fitted to the shank in the required attitude. The locking fingers perform their normal function of securing the fastener on the shank. The stabilising fingers are preferably spaced equi-angularly about the aperture and so are the locking fingers. The stabilising fingers may be alternated with the locking fingers. The fingers may be separated from one another by slits or by narrow slots. The closed ends of the slits or slots are preferably rounded to avoid incipient cracks. Slits may be rounded by terminating in circular holes pierced through the metal. The accompanying drawings shown one form of fastener according to the invention. In the drawings: Figure 1 is a plan view of the fastener, Figure 2 is a cross-section on line 2-2 of Figure 1 and Figure 3 is a cross-section on line 3-3 of Figure 1. The fastener is formed from spring steel sheet and has a continuous annular outer portion 3, with a peripheral flange 4, and an inner portion 5 divided into two locking finger 6 and two stabilising fingers 7 extending radially inwards towards an aperture 8 and separated by narrow slots 9 the closed ends of which are rounded. The two locking fingers 6 are diametrically opposite to one another and so are the two stabilising fingers 7 so that locking fingers and stabilising fingers alternate. The locking fingers 6 subtend a smaller angle at the centre of the aperture 8 than the stabilising fingers 7 and any grain of the spring steel runs parallel to the line 2-2. The back of the outer portion 3 forms a bearing surface 10. The locking fingers 6 from their roots at the Junction between the inner and outer portion 3 and 5 are inclined forwards from the plane of the bearing surface and have arcuate tips. The main parts of the stabilising fingers 7 remain in the plane of the bearing surface 10 as far as the aperture 8 but have extended tips 11 bent forwards and of tapering part-cylindrical shape. When, as indicated in Figure 2, the back of the fastener is over the end of a shank 12, the locking fingers 6 and stabilising fingers 7 yield to allow the shank to enter the aperture 8. The stabilising fingers 7 guide the fastener and keep its bearing surface at right angles to the shank axis. The locking fingers 6 resist withdrawal of the fastener in the opposite direction. The fastener may be fitted, as also indicated in Figure 2, with a domed cap 13 the free edge of which is closed over the back edge of the flange 4. WHAT WE CLAIM IS:

1. A sheet metal push-on fastener for gripping a smooth cylindrical shank, the fastener comprising an inner portion defining an aperture for receiving a cylindrical shank, and a continuous outer portion surrounding the inner portion, the inner portion comprising fingers all having their tips at the aperture, some of the fingers being locking fingers and others stabilising fingers interposed between the locking fingers, the locking fingers being inclined with respect to the axis of the aperture, and having arcuate edges at their tips, and the stabilising fingers having extended tips which are confined to the same side of the fastener as the locking fingers, the arrangement being such that, in use of the fastener, the fingers engage the cylindrical surface of a shank of predetermined size entered in the aperture and the locking fingers lie oblique to the said surface of the shank, and when the fastener is pushed along the shank in the direction in which the locking fingers trail their arcuate edges slide along the shank but when pushed in the opposite direction they grip the shank and resist relative movement, and the extended tips of the stabilising fingers embrace an axial extent of the shank so as to urge the fastener to remain in a predetermined attitude with respect to the axis of the shank, but such as not to resist relative movement when the fastener is pushed along the shank in said opposite direction.

fingers and one opposed pair of stabilising fingers.

6. A fastener as claimed in claim 5 wherein the locking fingers subtend a smaller angle at the centre of the aperture than the stabilising fingers.

7. A sheet metal push-on fastener for gripping smooth cylindrical shanks substantially as described herein with reference to and as illustrated by the accompanying drawings.