SPECIFICATIONStud for a panel fastenerThis invention relates to a stud for a panel fastener, and to a panel fastener incorporating such a stud.
A panel fastener is generally used to fasten a panel to a frame member, but can be used in many applications to fasten a panel to a second member.
The panel and the second member have aligned openings through which the stud can pass, with the head of the stud being toG large to pass through the opening in the panel. A receptacle is located on the rear side of the second member, and is generally bolted, riveted or otherwise attached to that member. Co-operable means are provided on the stud and on the receptacle which permit them to be coupled together, thereby fastening the panel to the second member.
When the stud and the receptacle are uncoupled, releasing the panel from the second member, the receptacle remains attached to the second member.
It is desirable to retain the stud on the panel, so that it is not lost when the fastener is uncoupled. This is particularly important in jet aircraft applications, where a stud could work its way out of the panel, and be ingested into the engine, thus causing damage to the engine.
There are several types of retaining ring presently available for retaining the stud of a panel fastener on the panel. All the known retaining rings are adapted to attach to the stud on the rear side of the panel, and all are larger than the opening in the panel, thereby preventing the stud from falling out through the opening. For example, retaining rings take the forms of wire rings and split 'C' rings. Such a ring opens to fit around the stud, and then closes to fit into a groove in the stud (or into a groove in the front of a widened portion of the stud), thereby attaching itself to the stud. Another known form of retaining ring is a spiral-type ring made of a resilient material which permits the ring to expand to fit around the stud and then contract to retain the stud.Yet another known type of retaining ring is a solid ring with tabs which flex in order to fit the tabs into slots in the stud, thereby attaching the ring to the stud.
All of these retaining rings have design characteristics which permit them to open and close, flex, expand or contract in order to be installed over the stud, and then to retain the stud in its panel. Such design characteristics, and the accompanying mate rial characteristics, such as the brittleness of spring steel, are characteristics which cause failure of the retaining rings in operation.
Most of these retaining rings work well when the stud is only moved axially. However, when the movement is angular or rotational (or a combination thereof), many retaining rings lose their capacity to adhere to the stud, particularly when that movement is accompanied by an axial force on the stud. Other conditions, such as a lack of a counterbored space between the panels for the retaining rings, or debris in the counterbored space, also cause failure of the rings. Occasionally, panels are required to slide slightly before the fastener can be engaged, which also causes failure of the rings.
The aim of the invention is to provide a stud for a panel fastener which does not suffer from these disadvantagesThe present invention provides a stud for a panel fastener, the stud comprising a cylindrical male portion, and a tubular sleeve adapted to fit over one end of the cylindrical male portion, the cylindrical male portion being provided with a head at the other end thereof, the tubular sleeve being formed with an integral enlarged portion having a maximum external dimension larger than the internal dimension of the rest of the tubular sleeve, and wherein means are provided for coupling the cylindrical male portion to the tubular sleeve.
Advantageously, the cylindrical male portion and the tubular sleeve both have circular cross-sections.
In one preferred embodiment, the tubular sleeve has an internal diameter slightly smaller than the external diameter of the cylindrical male portion, thereby to provide an interference fit between the cylindrical male portion and the tubular sleeve, the interference fit constituting said coupling means. In this case, the coupling means may further comprise an annular groove in the head, and the tubular sleeve is such that, when fitted over the cylindrical male portion, the end of the tubular sleeve fits into the annular groove. Preferably, the annular groove extends at a radially outward angle to the axis of the cylindrical male member.
In another preferred embodiment, the coupling means comprises complementary threads on the external surface of the cylindrical male portion and on the internal surface of the tubular sleeve, whereby the tubular sleeve may be threadably engaged by the cylindrical male portion.
Advantageously, the cylindrical male portion has an internal bore starting at said one end and extending axially into the cylindrical male portion.
Preferably, the stud further comprises a retainer for retaining the stud in position in an aperture in a panel.
In one preferred embodiment, the retainer is a solid, washer-like retaining ring which is slidable over the tubular sleeve, the retaining ring having an internal diameter smaller than the maximum external dimension of the enlarged portion of the tubular sleeve.
In another preferred embodiment, the enlarged portion of the tubular sleeve is a solid, annular portion, the enlarged portion constituting the retainer.
The invention also provides a panel fastener comprising a stud adapted to fit into an opening in a panel, and a receptacle engageable with the stud, wherein the stud is as defined above.
Preferably, the receptacle is provided with a projection adapted to fit into the internal bore provided in the cylindrical male portion of the stud.
Three forms of stud, each of which is constructed in accordance with the invention and is for a panel fastener, will now be described, by way of example, with reference to the accompanying drawings, in which Figure l is an exploded part-sectional side eleva tion of the first form of stud;Figure 2 is a perspective view of the first form of stud in the assembled condition;Figure 3 is a transverse cross-sectional view of the first form of stud in the assembled condition;Figure 4 is a transverse cross-sectional view of the second form of stud;Figure 5 is a transverse cross-sectional view of the third form of stud; andFigure 6 is a transverse cross-sectional view of a receptacle which can be used with the stud shown inFigure 4.
Referring to the drawings, Figures 1 to 3 show a two-part stud 38, a solid retaining ring 34, and a panel 36. The stud 38 has a cylindrical male portion 10 and a tubular sleeve 28. The cylindrical male portion 10 has a head 12 at one end, the head having a frustroconical outer surface 14. Alternatively, the head 12 may be of any shape provided it is too large to pass through an opening 16 in the panel 36. A groove 18 is formed in the head 12; the groove starting approximately where the head meets the cylindrical surface of the portion 10, and extending radially outward at an angle to the axis 20 of the cylindrical male portion 10. An internal bore 24 is formed in the cylindrical male portion 10, the bore starting at the free end 22 of the cylindrical male portion, and extending axially into the cylindrical male portion. Internal threads 26 are formed in the bore 24.The bore 24 and the threads 26 serve as means for coupling the stud 38 to a receptacle (not shown). Alternatively, the stud may be coupled to a receptacle by any other known suitable means.
The tubular sleeve 28 has a cylindrical internal surface 30, whose internal diameter is slightly smaller than the external diameter of the cylindrical male portion 10. It is to be understood that there may be complementary slots and grooves in the cylindrical surfaces 10 and 30, and that the cross-sections of the portion 10 and the sleeve 28 may be other than circular. At one end, the tubular sleeve 28 is formed with an annular enlarged portion 32, the external diameter of which is larger than the external diameter of the rest of the tubular sleeve. While an annular enlarged portion 32 is shown, it is not necessary that the enlarged portion be annular, as long as the retaining ring 34 cannot pass over it.The retaining ring 34 is shaped like a washer, and has an internal diameter larger than the external diameter of the tubular sleeve 28 and smaller than the external diameter of the enlarged portion 32. The external diameter of the retaining ring 34 is too large to pass through the panel opening 16.
The stud shown in Figures 1 to 3 is assembled as follows. The cylindrical male portion 10 is placed on the front side (that is to say the left-hand side as seen in Figure 1) of the panel 36, and in alignment with the panel opening 16. The retaining ring 34 and the tubular sleeve 28 are placed on the rear (right-hand) side 39 of the panel 36, and in alignment with the panel opening 16. The retaining ring 34 is then positioned around the sleeve 28. Then, eitherthe sleeve 28 or the cylindrical male portion 10 is pushed through the opening 16. The tubular sleeve 28 is then pushed onto the cylindrical male portion 10, sufficient force being applied to permit an interference fit. The free end of the tubular sleeve 28 deforms to fit into the groove 18, and the sleeve 28 and the cylindrical male portion 10 are thereby coupled together.Other means for coupling may be used instead of that described above. For example, the cylindrical male portion 10 and the tubular sleeve 28 may be bonded together with glue, or complementary screw threads may be provided within the tubular sleeve and on the cylindrical male portion, as will be described later.
The functions of the stud 38, the panel 36 and the retaining ring 34 will now be described. The internal threads 26 in the cylindrical male portion 10 permit it to be coupled to a receptacle, as will be described later. When the stud 38 and the receptacle are uncoupled, the the stud is prevented from working its way out of opening 16 from the rear 39 to the front 37 by the retaining ring 34. This is because the retaining ring 34 cannot slide over the enlarged portion 32 (as its internal diameter is smaller than the external diameter of the portion 32), and the retaining ring cannot pass through the opening 16 (as the external diameter of the retaining ring is larger than the diameter of the opening). The head 12 prevents the stud 38 from working out of the opening 16 from the front 37 to the rear 39, because it is too large to pass through.Thus, the stud 38 is retained in the panel 36. Since the retaining ring 34 does not have to be flexible in order to be installed on the stud 38, it does not have the previousiydiscussed flexible properties which would make it susceptible to failure.
Figure 4 shows a second form of stud 38'. The stud 38' is similar to the stud 38, so like reference numerals have been used for like parts. The stud 38' can be retained in the panel 36 without using a separate retaining ring 34. Thus, the enlarged portion 32 of the tubular sleeve 28 is made to serve as a retaining ring by making it large enough so that it will not pass through the opening 16. Again, the enlarged portion 32 is less flexible and sturdier than known retaining rings in order to avoid the failures associated with such rings. Slots 27 are formed in the cylindrical male portion 10, these slots being used to connect the stud 38' to the receptacle 44 shown in Figure 6, as will be explained later.
Figure 5 illustrates a third form of stud 38". The stud 38" is similar to the stud 38, so like reference numerals have been used for like parts. In this embodiment, the cylindrical male portion 10 is provided with external threads 40, and the tubular sleeve 28 is provided with complementary internal threads 42. The threads 40 and 42 permit the sleeve 28 to be threaded to the portion 10, this threaded coupling being instead of the interference fit coupling of the embodiment of Figures 1 to 3. In this embodiment, a groove of the type shown at 18 inFigure 1, is not necessary.
Figure 6 illustrates a receptacle 44 which is adapted to be coupled to the stud shown in Figure 4.
The receptacle 44 is riveted to a backing member 46 by rivets 48, and is located behind an opening 49 in the member 46. The receptacle 44 has a cup-like portion 50, which is provided with a projection 52.
The projection 52 has external threads 54 on its outer surface, and is adapted to fit into the bore 24 and the cylindrical male portion 10 of the stud 38'. In this position, the threads 54 on the projection 52 mate with the threads 26 in the bore 24, thereby coupling the stud 38' to the receptacle 44. The receptacle 44 is provided with locking lugs 29 which mate with the slots 27 in the stud 38' to lock the stud to the receptacle 44. Obviously, the receptacle 44 (or modifications thereof) could be used with the studs 38 or 38" of Figures 1 to 3 and Figure 5 respectively.
The receptacle 44 shown in Figure 6 is shown only as a preferred form of receptacle that can be used in conjunction with the studs 38, 38' or 38". Obviously, other suitable forms of receptacle could be used instead.