GB2345871A

GB2345871A - A lens jig

Info

Publication number: GB2345871A
Application number: GB9928018A
Authority: GB
Inventors: Philip Russell Bareham
Original assignee: CAMBRIDGE OPTICAL GROUP LIMITE
Current assignee: CAMBRIDGE OPTICAL GROUP LIMITE
Priority date: 1998-12-01
Filing date: 1999-11-26
Publication date: 2000-07-26
Also published as: GB9928018D0; GB9826379D0

Abstract

A lens jig 10 comprises two parts between which a lens can be retained, including guide means for guiding hole forming means used to form holes in the lens, and positioning means for locating the two parts relative to each other so that the guide means are correctly positioned. Preferably the jig is provided with a base plate 20 and a top plate 30. The jig may be provided with pegs, eg dowels 60, each peg being associated with one part, and cooperable with a complementary hole 70 in the other part. Preferably the guide means comprises bushes 90 that fit into associated apertures 80 in the top plate, and the top plate may also have slots (130, fig 8) which align with corresponding slots in the base plate (140, fig 8) to enable the hole forming means to form at least one slot extending inwardly from the inward edge of the lens. The lens jig may be used for making holes in rimless spectacles.

Description

LENS DRILLING JIG This invention relates to a jig for holding lenses that require holes drilling in them, particularly those for rimless spectacles.

As part of the production of rimless spectacles holes are drilled into the lenses for receiving screws, and the frame components, such as the sides, the bridge and the pad arms, are attached by means of these screws.

A jig needs to be used to hoid a lens steady whilst the holes are being drille.

A problem with existing ways of producing holes in lenses for rimless spectacles is that the holes produced may be misshapen causing wastage.

A known jig described in Gebrauchsmuster DE 297 10 664 U1 includes a circular member with a convex upper surface from which a pair of mutually parallel diametrically opposed posts project. A first template is located on the upper surface of the circular member by means of the posts, a single lens is mounted on the first template and a second template with drill bit guiding holes is mounted thereon and located relative to the circular member and the first template by means of the posts. Bushes can be located in the drill bit guiding holes. The jig includes a base on which the circular member is mounted so that it can rotate and tilt.

The above described jig cannot prevent misalignment of a lens being drilled and a drill bit. Furthermore, the jig includes four basic components, namely the first and second templates, the circular member with posts which is necessary to hold the templates correctly juxtaposed and the base. It would be desirable to provide a jig which is easier to manufacture and use.

It is therefore an object of the present invention to provide a jig that alleviates at least one of the above mentioned problems.

According to the present invention there is provided a lens jig comprising two parts between which a lens can be fixedly retained, the parts including guide means for guiding hole forming means used to form holes in the lens and positioning means for locating the two parts relative to each other so that the guide means are correctly positioned.

It may be desirable for the positioning means to comprise a plurality of pegs, each peg being associated with one part, each peg being cooperable with a complementary hole in the other part. The positioning means are preferably positioned asymmetrically with respect to the jig parts.

One part could include a recess that is shaped to accommodate a lens.

It may be desirable for a lens to be placed in the recess with its convex surface face down.

The jig is preferably configured to retain a pair of spectacle lenses that require holes forming in them in order that both lenses can be drilled in a single operation and in order that lenses can be reliably and accurately juxtaposed relative to each other during the drilling operation. This will ensure that holes for mounting a bridge member can be correctly positioned with ease.

One of the parts preferably includes guiding means for guiding hole forming means into holes in each lens. It may be desirable for the guiding means to comprise bushes that can fit into associated apertures in one of the parts. The bushes are preferably made of hardened steel.

The two main parts between which the or each lens is retainable could advantageously be made of Tufnel (RTM).

One embodiment of the present invention will now be described by way of example with reference to the accompanying figures, in which: Figure 1 is an exploded isometric view of the jig according to one embodiment of the invention ; Figure 2 is a plan view of the base plate of the jig shown in Figure 1 ; Figures 3 and 4 are sectional views along the lines 3-3 and 4-4 respectively of the base plate shown in Figure 2; Figure 5 is a plan view of the top plate of the jig shown in Figure ; Figure 6 is a sectional view of a drilling bush placed in the top plate ; Figure 7 is a view similar to a view of part of Figure 4 and illustrates part of a modified base plate ; Figure 8 is a sectional view of part of a modified jig; Figures 9 and 10 are sectional views along the lines 9-9 and 10-10 respectively of the jig shown in Figure 8.

Referring to Figures 1 to 5 of the accompanying drawings, a lens drilling jig 10 includes a rectangular base plate 20 and a rectangular top plate 30 that is of substantially the same length and width but not necessarily of the same thickness as the base plate.

The base plate 20 includes two recesses 40 that are respectively shaped to receive each of a pair of rimless spectacle lenses. Towards the bottom of each recess is a continuos ledge 50 for supporting a lens. The surface of the ledge for receiving a lens is curved to the shape of a typical lens. The recess otherwise extends right through the plate so that each ledge so surrounds a through opening in the base plate 20. Two dowels 60, preferably of metal, project out of the base plate. Each of these dowels is located close to one of two opposing corners of the base plate and are positioned asymmetrically to each other so as to prevent the top and base plates from being incorrectly juxtaposed when assembled.

The top plate 30 includes two holes 70 for receiving the two respective dowels 60 of the base plate 20. The top plate also contains four additional holes 80 into each of which a headed drilling bush 90 can be inserted.

Referring to Figure 6, the headed drilling bush 90 is cylindrical in shape.

The bush has a circular hole 100 that is centred on the longitudinal axis of the bush and passes through it. The entrance 110 to the hole in the head 120 is cone shaped to guide a drill bit into the hole. The hole preferably has a diameter of 1.3mm. The bush is preferably made of hardened steel.

Referring particularly to Figure 1, the holes 80 for receiving the drilling bushes 90 are located so that the hole 100 in the centre of each bush coincides with one of the positions of a hole to be drilled into one of the lenses (not shown) placed in the jig 10. In the described embodiment a hole would be drilled on each side of each lens placed in the jig.

Both the base plate 20 and the top plate 30 are preferably made of Tufnel (RTM).

A separate set of top and base plates may be provided for each size of each model of rimless spectacles.

In use, a pair of lenses of the required optical property are placed with their convex surface face down in the respective recesses 40 of the base plate 2û of the jig 10. The lenses will have aiready been cut to the required dimensions on conventional edging equipment. The top plate 30 is placed on top of the base plate so the dowels 60 fit into their respective holes 70 and the two plates are coincident to one another. The drilling bushes 90 are then placed in their respective holes 80 in the top plate with the heads 120 uppermost.

The jig 10 is placed under a conventional pillar drill (not shown) in such a position so that the drill bit of the drill is directly above the hole 100 in one of the bushes 90. A 1. 3mm drill bit is preferably used. The drill is switched on and the drill bit is lowered into the hole 100 so that it drills a hole right through the lens. This is repeated for all the other drilling bushes.

An advantage of the jig 10 described is that holes can only be drilled in the correct position in the lenses when the top plate 30 is coincident with the base plate 20 and the dowels 60 fit into their respective holes 70.

Using drilling bushes leads to minimal variation in the diameter of the holes drilled in the lenses as the drill bit is effectively prevented from bending and hence producing holes that are wider than the drill bit and irregular in shape. Also, the risk of the drill bit breaking is reduced by preventing the drill bit from bending.

It is also advantageous that the jig 10 can be quickly set up as it contains few parts and accurate holes can be drilled rapidly. The precise location of the drill holes can be repeated for a large number of identically shaped lenses. The precise location of the drill holes also means that frame components are accurately positioned on the lenses. High productivity is thus achieved using the jig 10.

In a modification shown in Figure 7, the surface of the continuos ledge 50a has a pair of aligned ridges 55 on opposite sides of the through opening, the ridges being located approximately midway along either side of the through opening. This enables a lens placed with its convex surface face down in a recess 40a to be tilted about the pair of ridges 55 so that the drill bit is substantially perpendicuiar to the concave and convex surfaces of the lens when the drill bit drills the holes in the lens.

In another modification shown in Figures 8 to 10, the top plate 30a has a slot 130 extending from the edge of hole 80a and the base plate 20a has a slot 140 extending from the edge of the recess 40b, the slots 130,140 being aligned when the top plate 30a is placed on top of the base plate 20a. The headed drilling bush 90a has a slot 150 recessed down one side and this slot can be aligned with the slots 130,140 so that the aligned slots are able to receive a drill bit or a milling device for drilling a slot from the edge of a lens held in the recess 40b. A bush slot alignment device may also be provided so that the slot 150 in the bush 90a is always aligned with the slot 130 in the top plate 30a when the bush is placed in the hole 80a.

Whilst one particular embodiment has been described above it will be understood that various modifications may be made without departing from the scope of the invention. For example, the jig has been described for use with a conventional drill, but other hole forming means could be used such as lasers. Four holes 80 have been shown in the top plate 30 but more or less holes may be employed according to how many holes are required in each lens. There may be any number of recesses 40 in the base plate to receive a respective number of lenses. There are a variety of alternatives to the two asymmetrical dowels 60 and complernentary holes 70 for ensuring that the two plates are correctly located relative to one another. Such alternatives include a single off-centre square peg and a complementary hole, or a ridge or ridges placed on or near the edge of one plate and so shaped or positioned to prevent mis-location of the other plate. Also pegs or ridges may not be limited to just one plate for example each plate may include one peg and one hole which respectively engage a hole and a peg of the other plate.

Claims

CLAIMS : 1. A lens jig comprising two parts between which a lens can be fixedly retained, the parts including guide means for guiding hole forming means used to form holes in the lens and positioning means for locating the two parts relative to each other so that the guide means are correctly positioned.
2. A tens jig as claimed in claim 1, wherein the positioning means comprises a plurality of pegs, each peg being associated with one part, each peg being cooperable with a complementary hole in the other part.
3. A lens jig as claimed in claim 1 or 2, wherein the positioning means is positioned asymmetrically with respect to the jig parts.
4. A lens jig as claimed in any preceding claim, wherein one part includes at least one recess, the or each recess being shaped to accommodate a lens.
5. A lens jig as claimed in claim 4, wherein the or each recess is shaped to receive a lens placed in the recess with its convex surface face down.
6. A lens jig as claimed in claim 4 or 5, wherein the or each recess includes lens tilting means so that a lens placed in the recess may be tilted to enable the hole forming means to form holes substantially perpendicular to the lens.
7. A lens jig as claimed in claim 6, wherein the lens tilting means comprises contouring of a ledge in the or each recess.
8. A lens jig as claimed in any preceding claim, wherein one part includes the guide means for guiding hole forming means.
9. A lens jig as claimed in claim 8, wherein the guide means comprises bushes that can fit into associated apertures in said one part.
10. A lens jig as claimed in any preceding claim, wherein the parts including the guide means have slots to enable the hole forming means to form at least one slot extending inwardly from the edge of a lens held in at least one said recess.
11. A lens jig as claimed in claims 9 and 10, wherein at least one bush has an inwardly extending slot.
12. A lens jig as claimed in claim 11, wherein each corresponding aperture includes a slot extending outwardly therefrom which the slot in the bush is adapted to be aligned with.
13. A lens jig as claimed in claim 12, wherein at least one said recess includes at least one slot extending outwardly therefrom, the or each slot adapted to align with a said corresponding slot in a said aperture.
14. A lens jig constructed as substantially hereinbefore described with reference to the accompanying drawings.