GB2090627A

GB2090627A - Stud and socket fastener assembly

Info

Publication number: GB2090627A
Application number: GB8138911A
Authority: GB
Original assignee: Rexnord Inc
Current assignee: Rexnord Inc
Priority date: 1981-01-05
Filing date: 1981-12-24
Publication date: 1982-07-14
Also published as: FR2497548A1; DE3150836A1

Abstract

A fastener assembly 10 comprises a generally cylindrical socket 16 and a stud 18. The socket 16 has an internal through bore 29, with a pair of helical ramps 31 and 33. On its surface, each starting adjacent to one end of the bore 29 and terminating adjacent to the other end where the socket 16 is provided with detents 30. The stud 18 has a head 19, a shank 20, and a cross pin 21 positioned adjacent to the end of the shank remote from the head. The cross pin 21 is dimensioned to move axially and rotatably along the helical ramps 31 and 33 in response to rotational movement imparted to the head 19 of the stud 18, and also to rest in the detents 30. A spring 22 is operatively associated with the shank 20 to urge the stud 18 away from the receptacle 16. The stud is positively driven during fastening and releasing actions. <IMAGE>

Description

SPECIFICATION Fastener assembly This invention relates to a fastener assembly for connecting a panel member to a frame, and more particularly to such a fastener assembly which provides a positive drive during both engagement and disengagement of the assembly.

Fastener assemblies of the type with which the present invention is concerned are quite widely used. Typically such a fastener assembly includes a receptacle secured to a frame member, and a stud which can be inserted through the panel member and secured to the receptacle. Fastacting fastener assemblies of this type are commonly referred to as quarter-turn fasteners.

Quarter-turn fasteners include a stud having a cross pin through the shank of the stud. The cross pin is dimensioned and positioned on the stud to ride over a cam, and to fit into a recess or detent at the end of the receptacle. A spring is usually mounted on the stud to bias the stud away from the receptacle, thereby securing the stud in the receptacle.

This type of fastener assembly is generally quite acceptable. However, in certain applications, several drawbacks become apparent. One such application is when a fastener assembly of this type is used to secure printed circuit boards.

Usually these boards have electrical connector pins which engage electrical sockets. Care must, therefore, be taken, upon engagement and disengagement of the fastener, to avoid bending the connectors. Existing fastener assemblies provide no positive driving force during disengagement, so removal of the electrical connectors from their respective sockets is accomplished manually. This increases the possibility of damaging the connectors during engagement and disengagement.

The aim of the invention is to provide a fastener assembly that provides a positive drive during both engagement and disengagement.

The present invention provides a fast-acting, bidirectional, positive-drive fastener assembly comprising a generally cylindrical receptacle and a stud, the receptacle having an internal through bore, a helical ramp being provided on the internal surface of the receptacle which defines the bore, the helical ramp starting at a first point adjacent to one end of the bore and terminating at a second point adjacent to one end of the bore and terminating at a second point adjacent to the other end of the bore, the receptacle being provided with detent means at said other end of the bore, the stud having a head, a shank extending from the head, and a cross pin positioned adjacent to the end cf the shank remote from the head, the cross pin being dimensioned to move axially and rotatably along the helical ramp in response to rotational movement imparted to the head of the stud, and the cross pin being dimensioned to rest in the detent means, wherein a spring is operatively associated with the shank to urge the stud away from the receptacle.

Advantageously, a second helical ramp is provided on the internal surface of the receptacle which defines the bore, the second helical ramp starting at a first point adjacent to said one end of the bore and terminating at a second point adjacent to said other end of the bore.

Preferably, said second point of the or each helical ramp is diametrically opposed to the first point of that helical ramp.

Conveniently, the detent means is constituted by a pair of detents provided on the receptacle adjacent to said other end of the bore.

One form of fastener assembly constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a part-sectional cross sectional view of the fastener assembly shown connecting a panel member to a frame member, Figure 2 is a side elevation of part of the fastener assembly of Figure 1; and Figure 3 is a cross section taken on the line 3-3 of Figure 2.

Referring to the drawings, Figure 1 shows a fastener assembly 10 connecting a panel member 12 to a frame member 14. The fastener assembly 10 includes a stud 18 and a receptacle 1 6.

The stud 1 8 has a head 19, and a shank portion 20 extending from the head. The shank 20 extends from the head 1 9 for a distance substantially equal to the length of the receptacle 1 6 plus the thickness of the frame 14 and the thickness of the panel 12. The shank 20 is provided with a cross pin 21 adjacent to its free end, the cross pin extending transversely through the shank. The head 19, together with encapsulation means 23, forms a space into which a spring 22 is positioned. The spring 22 biases the head 1 9 away from the panel 12. A retaining ring 25 is positioned around the shank 20, between the cross pin 21 and the head 19, to retain the stud 1 8 with the panel 12 upon disengagement of the stud from the receptacle 1 6.

The receptacle 1 6 defines a generally cylindrical member having mounting flanges 26 extending radially therefrom at one end. The mounting flanges 26 are used to attach the receptacle 1 6 to the frame member 14 by rivets 27 or other known means. The receptacle 1 6 is axially aligned with the stud 1 8 so that, upon passage through a hole 24 in the panel 12, the shank 20 of the stud fits into an internal bore 29 of the receptacle 1 6. The receptacle 1 6 terminates in two detents 30, into which the cross pin 21 of the shank 20 rests upon engagement of the fastener assembly 10.

As shown in Figure 2, the receptacle 1 6 has its internal bore 29 machined to define two helical ramps 31 and 33, on which the cross pin 21 of the stud 1 8 rides during both engagement and disengagement of the fastener assembly 10. The provision of two helical ramps 31 and 33 enables both ends of the cross pin 21 to ride on its own helical ramp 31 or 33.

In order to retain as much of the fast-acting qualities associated with similar fasteners of this type, and still provide positive drive during engagement and disengagement, the pitch of the helical ramps 31 and 33 should be greater than that of known threaded fasteners, but not so great as to require excessive axial force to be applied to the stud 1 8 during engagement of the fastener assembly 1 0.

Preferably, each helical ramp 31 and 33 starts at a given point of the internal bore 29 and terminates at a point axially spaced from, and diametrically opposite to, that start point. This particular configuration has been found to provide adequate positive drive during both engagement and disengagement, while retaining the fastacting qualities of similar fastener assemblies not having the helical ramps 31 and 33.

As shown in Figure 3, the base of the receptacle 1 6 terminates in two detents 30 adjoined by stops 32. It can be seen that, as the cross pin 21 leaves the helical ramps 31 and 33, it rotates to rest in the detents 30. In this position, the fastener assembly 10 is locked, as the spring 22 urges the stud 18 away from the receptacle 16, thereby retaining the cross pin 21 in the detents 30.

It will be readily understood that, due to the helical ramps 31 and 33 formed within the internal bore 29 of the receptacle 16, the stud 1 8 is positively driven during both engagement and disengagement of the fastener assembly 10. The cross pin 21 is retained within the helical ramps 31 and 33 to provide the postive drive in both directions.

There is thus provided a fastener assembly 10 that provides positive drive during both engagement and disengagement, while retaining substantially all of the fast-acting qualities of known fasteners of this type.

Claims

1. A fast-acting, bi-directional, postive-drive fastener assembly comprising a generally cylindrical receptacle and a stud, the receptacle having an internal through bore, a helical ramp being provided on the internal surface of the receptacle which defines the bore, the helical ramp starting at a first point adjacent to one end of the bore and terminating at a second point adjacent to the other end of the bore, the receptacle being provided with detent means at said other end of the bore, the stud having a head, a shank extending from the head, and a cross pin positioned adjacent to the end of the shank remote from the head, the cross pin being dimensioned to move axially and rotatably along the helical ramp in response to rotational movement imparted to the head of the stud, and a cross pin being dimensioned to rest in the detent means, wherein a spring is operatively associated with the shank to urge the stud away from the receptacle.

2. A fastener assembly as claimed in claim 1, wherein a second helical ramp is provided on the internal surface of the receptacle which defines the bore, the second helical ramp starting at a first point adjacent to said one end of the bore and terminating at a second point adjacent to said other end of the bore.

3. A fastener assembly as claimed in claim 1 or claim 2, wherein said second point of the or each helical ramp is diametrically opposed to the first point of that helical ramp.

4. A fastener assembly as claimed in any one of claims 1 to 3, wherein the detent means is constituted by a pair of detents provided on the receptacle adjacent to said other end of the bore.

5. A fast-acting, bi-directional, positive-drive fastener assembly substantially as hereinbefore described, with reference to, and as illustrated by, the accompanying drawings.