TECHNICAL FIELD

This invention relates to joinery fittings and in particular lockable latch bolts and similar mechanisms suitable for use with joinery.

BACKGROUND OF THE INVENTION

Joinery is typically fabricated from either lengths of solid timber or lengths of hollow metal, in particular aluminium, extrusions. Such joinery often involves slideable elements such as doors or windows that in an opened mode overlap one another. To this end various joinery fittings utilised therein are preferably "flush" mounted to avoid or limit contact when the parent components are overlapped. Herein the term "flush" is used to cover both fully recessed and substantially recessed. More particularly, fully recessed is where the obverse face of the fitting is co-planar with the surrounding face of the parent substrate material. This approach is typically used with timber joinery, a cavity being formed in the substrate material to receive the internal mechanism of the fitting and a rebate formed in the edge of the substrate material about the cavity to take a face plate of the fitting. Substantially recessed is where a face plate of the fitting seats on the rim defining a cut-out formed in the wall of a hollow substrate material. The cut-out provides access to the hollow interior of the substrate material and in which the internal mechanism of the fitting is located. . This approach is typical of flush mounted fittings provided for and in hollow aluminium joinery.

An intention of this invention is to provide a flush mountable lockable latch bolt fitting particularly suitable for use with both timber and aluminium joinery. A further object is to provide the public with a useful choice.

DISCLOSURE OF INVENTION

According to a first embodiment of this invention there is provided a latch bolt fitting broadly comprising a casing having a flush mountable face plate by which the casing ;an be mounted within a cavity of a parent object adjacent to an end thereof, the casing incorporating tracks in which a slide, supporting a bolt projecting from an end thereof, is longitudinally slideably enabling the bolt to be extended and returned, a locking mechanism supported by the slide and incorporating a latch to engage a detent on the casing as to lock the bolt in an extended mode, the tracks being set-in from a locking mechanism access aperture provided in the face plate such that the locking mechanism projects toward the access aperture no more than as to be flush with the face plate, means for mounting the fitting being provided on the rear face of the face plate.

According to a second embodiment of this invention there is provided a latch bolt as described in the preceding paragraph wherein the mounting means comprise wedging elements provided on the rear side of the face plate adjacently inward of both ends thereof, one wedging element being fixed and the other being longitudinally extendable, whereby in situ the fitting can be mounted by presenting the fixed wedging element to a first mounting element of a parent object to seat the mounting element between that wedging element and the rear side of the face plate and the extendable wedging element then extended to similarly seat a second mounting element on the parent object and positioned opposite the first mounting element, therebeneath and with further extension of the extendable wedging element impinge the mounting elements between the wedging elements and the rear side of the face plate to retain the fitting to the parent object.

BRIEF DESCRIPTION OF THE DRAWINGS.

Fig. 1 is an exploded perspective view of the fitting, and

Fig Ia is a cross-section view on line A-A on Fig 1, and

Fig. 2 is a partly exploded perspective view to show the fitting as partly assembled and,

Fig. 3 is a perspective view of the assembled fitting, and

Fig 4 is a perspective view of the rear side of a face plate of the fitting, and

Fig. 5 is a side elevation of the fitting mounted to a hollow parent element, and

Fig. 6 is a partly exploded perspective view of the fitting in readiness for mounting in a cavity of a solid parent element. DETAILED DESCRIPTION OF THE INVENTION

An elongate casing 1 is preferably formed from a length of aluminium extrusion with a "U"-shaped cross-section opening, as at 2, at a front thereof. A face plate 3 is preferably zinc die cast and seats over the longitudinal opening 2 of the casing 1 and preferably extends beyond both ends Ia, Ib thereof. An elongate locking mechanism access aperture 4 is formed through the face plate 3, on the rear side 3a of the face plate 3 the aperture 4 preferably being surrounded by a wall 5. Screws 6 are preferably inserted through the back of the casing 2 to engage in spigots 7 (see Fig 4) provided on the rear side 3 a of the face plate 3 to detachably retain the casing 1 and face plate 3 together.

A pair of tracks 8 are provided one each on each of the internal faces Ic of the opposing walls of the casing 1. The tracks 8 are preferably extruded as an integral part of the casing 1 in the form of two opposing channels. The tracks 8 are set-back from the front opening 2 of the casing 1 as described in more detail below. A slide 9, preferably in the nature of a die cast elongate block, is slideably mounted in the tracks 8. Preferably spring loaded balls 10 are mounted in the sides of the slide 9 to provide a "glide fit" of the slide within the tracks 8. A detent 11 is provide on a lower end of the slide 9 to abut a web 12 formed between the lower spigots 7 on the face plate 3 to limit the extension of the slide 9 from the casing 1. A bolt 14 is carried by the slide 9, the bolt 14 projecting from a lower end thereof. Preferably a detachable extension 14a is provided on the bolt 14 enabling the overall length thereof to be readily adjusted. With sliding movement of the slide 9 the bolt 14 can be extended and returned as described in more detail below.

A locking mechanism, preferably a key operated barrel type 15, is mounted on the slide 9. To that end, preferably a boss 9a is formed on the obverse or front side of the slide 9, the boss 9a preferably being a close but free fit between the lateral sections of the wall 5. Preferably the height of the boss 9a is commensurate with the height of the wall 5, the combination substantially closing-off the inner extremity of the opening 4. A barrel 15a of the locking mechanism 15 is mounted in the boss 9a and through the slide to project clear of the rear side of the slide 9 as to extend beyond of the tracks 8. A latching arm 15c is mounted on the rear of the barrel 15 as to be engageable with a inwardly projecting detent 16 (see Fig Ia) formed in the side of the casing 1 behind the tracks 8 to enable the locking of the bolt 14 in an extended position. As an alternative to the detent 16 slots (not depicted) maybe formed in the wall of the casing 1 in which the arm 15c may be engaged... The positioning of the tracks 8 provides that the boss 9a projects into the face plate opening 4 no more than as to be flush with the obverse or front face 3a of the face plate 3.

Referring in particular to Fig. 4 and as described in more detail below, to enable mounting in situ wedging means 17 are provided on the rear side 3 b of the face plate 3. More particularly, preferably a pair of laterally spaced apart fixed undercut tabs 17a are provided adjacently inward of the lower end of the face plate 3 to form notches 17c with the rear side3b of the face plate 3. As described in more detail below, in situ the notches 17c seat on a mounting element 18 of a parent object. Adjacently inward of the upper end of the face plate 3 a longitudinally adjustable slide 19 is mounted. Slide 19 is of an "H" shape with preferably an "Alan key" adjustment cap-screw 20 being mounted through the transverse arm 19a thereof. A head of the cap-screw 20 is mounted for free rotation in a cavity 21 formed by an extension of wall 5, a cut-out 22 being formed in the wall 5 to enable access for an "Alan Key" through the opening 4 of the face plate. The inner end set of the arms of the slide 19 straddle the recess forming extension of wall 5 and the outer end set of arms straddle the spigot 7 to provide a guide for the slide 19. As with the mounting means 17 at the other end of the face plate 3 the outer ends of the outer end set of arms are formed with undercuts 17b to form notches 17c with the rear side 3b of the face plate 3.

Referring particularly to Figs 4 and 5, in mounting the fitting to a hollow parent component such as a typical upright frame member 23 of an aluminium door the fitting is presented to an appropriately cut opening 24 in the front wall 23a of the frame member 23. The rim 18 of the wall 23a defining the lower end of the opening 24 forms the mounting of the parent door and is seated within the undercuts 17c. In so doing the face plate 3 is disposed flush with the wall 23a as depicted in Fig. 5 and an "Alan key" can be inserted through the aperture 5 in the face plate to access the cap-screw 20 to extend the slide 19 until the rim section 18b of aperture 24 is seated within the undercuts 17b. Further extension of slide 19 wedge mounts the fitting between the rims 18 and 18b. Referring to Fig 6 should it be required to use the fitting with solid timber joinery separate upper and lower blocks 25 are first fastened into the ends of a typical cavity 28 formed in the parent door or window 29. The blocks 25 include lips 26 and 26b to replicate the rims 18 and 18b enabling mounting substantially as aforesaid. In so doing the face plate 3 may be seated on the rim, which may be rebated in known manner, of the cavity 28 or set into the cavity 28. Preferably for ease of manufacture the blocks 25 are identical and each includes an aperture 27 to align with the bolt 14. Preferably a bottom plate 30 is utilised on the underside of the parent door.