ANODISING JIG

Abstract: A jig or carrier for supporting and transporting hollow items through an anodising process comprising an electrically conductive rigid sheet (10) preferably pierced and pressed to produce nests (11) of integral prongs (12) the three prongs of each nest acting together resiliently to support an upturned cylindrical item (13) to be anodised. The sheet is preferably of stepped formation as at (14) and the nests of prongs (12) are geometrically arranged to maximise the capacity to support preferably in excess of 400 separate items (13). Each jig has side plates (17) for mounting on a frame cassette (23) adapted to support some 20 or more jigs for simultaneous passage through an anodising process. Jigs produced in this way are relatively inexpensive and require no maintenance when compared with conventional jigs for the purpose.

Description: ANODISING JIG THIS INVENTION concerns a jig or carrier for supporting and transporting hollow items through an anodising process. Such items include, for example, overcaps, shrouds, collars and sleeves produced from aluminium and used, for example, as necks and closures on perfume bottles, lipstick and other cosmetic containers and the like. Such an item usually consists of a pressed hollow cup or sleeve of generally cylindrical form produced from aluminium and anodised to provide a glossy, matt or semi-matt surface finish which may be coloured as required. The items are produced in vast quantities simultaneously, first being pressed out from the mother sheet and then manually mounted on jigs to be transported through de-greasing, anodising and finishing baths and then stripped off and packaged for dispatch to the customer. During this process the items, which are fragile, must be handled with extreme care, and in order to ensure that the anodising process is properly conducted there must be a firm electrical contact between each item and its jig and between the jig and the electro-chemical anodising system. Conventionally, such items are carried on a jig which consists essentially of a spine or bar of an electrically conductive material having a longitudinal array of holes at predetermined pitch spacings through which are placed flat or wire-form spring clips usually of titanium and being of sufficient resilience to retain the item as a resistance fit on the clip with adequate electrical contact therebetween but without causing deformation of the item. The spring clips are swaged where they pass through the bar or spine in order to ensure a rigid fit and a firm electrical contact therewith, and experience has shown that these bars and clips require regular maintenance in order to maintain accurate fit and alignment of the clips and adequate resilience thus to prevent the items from becoming dislodged during the anodising process. Thus, maintenance of these jigs requires considerable man power and indeed a continuous work force involved in the repair and replacement of the bars and spring clips. Some seventy-two spring clips, onto each of which is placed an item to be anodised, are provided on each bar and some twenty-eight bars are mounted on a carrying frame. Several such carrying frames are carried along the anodising line in which they are progressively dipped into sequential electro-chemical baths to perform the anodising and the finishing processes. Although the spring clips are themselves durable they tend to become loosened within the holes in the bars thus reducing the integrity of the electrical conductivity of the system and causing the clips to become misaligned and in some cases distorted with the result that items become dislodged during treatment. In turn this causes carry-over of liquids (retained within the items) from bath to bath and loss of production rates due to contamination of chemicals and actual loss of product items. According to the present invention there is provided a jig for supporting and transporting hollow items through an anodising process comprising an electrically conductive rigid sheet from at least one surface of which extends an array of nests of prongs upstanding from a planar surface of the sheet, each nest comprising two or more prongs mutually disposed and having sufficient resilience to retain a hollow item as a resistance fit thereon. Preferably, the prongs are provided by piercing and deformation of the rigid sheet thus to be integral with and upstanding from the surface thereof. Preferably, the planar surface of the sheet is stepwise formed such that the nests of prongs thereon are angularly displaced from the general plane of the sheet whereby the items may be held at an inclined attitude thereon. Still further, each nest comprises three angularly displaced prongs produced by piercing the sheet linearly about each nest and pressing the prongs upwardly therefrom, the prongs having inwardly curved tips to facilitate loading of the items thereon. Still further, each prong may include a projection in a base region to provide a stop whereby items are placed on the jig at a pre-determined distance from the general planar surface thereof. An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Fig. 1. is a plan view of a jig made in accordance with the invention and showing two rows of items to be anodised, placed thereon; Fig. la is a cross-sectional view taken on line A-A of Fig. 1; Fig. 2 is an enlarged plan view of part of the jig illustrated in Fig. 1; Fig. 2a is an enlarged section taken on line A-A of Fig. 2; Fig. 3 is a view illustrating a step-wise deformation of the jig in rows such that items carried thereon are disposed at an inclined attitude with respect to the general plane of the jig; Fig. 4 is a view similar to Fig. 3 showing the attachment of a side plate; Fig. 5 is a complete side or edge view of a jig loaded with items to be anodised; Fig. 6 is an underside or rear view of a completed jig; Fig. 7 is an isometric view of a frame cassette adapted to carry several jigs through an anodising process; and Fig. 8 is an enlarged isometric view illustrating a part of a jig mounted on the frame cassette and carrying rows of items to be anodised. Referring now to the drawings, a jig made in accordance with the invention is comprised of a sheet or tray 10 preferably of titanium or titanium alloy having pressed therefrom in a predetermined geometric pattern, a plurality of rows of nests 11 formed as upwardly projecting prongs 12, each nest 1 1 comprising three prongs 12 arranged at 120° spacing about a central axis in order to support a hollow cap or item 13 to be anodised. It will be seen from Figs. 1 and la that the geometric pattern in which the nests are arranged on the sheet 10, such that the nests of one row are offset laterally from the nests in the next adjacent row, maximises the number of items to be carried on the jig with adequate spacing therebetween. Each jig may carry in excess of 400 items. For example, the sheet or tray 10 may provide some forty-six rows each of nine nests whereby 414 items may be carried thereon. Figs. 2 and 2a provide a clearer illustration of how the prongs 12 are formed by linear piercing and deformation of the plate and bending the resultant prongs upwardly, preferably with inwardly disposed tips 12b to provide ease of loading of the items 13. The formation of the prongs upstanding from the sheet 10 is provided by a single pressing operation. If required, one or all of the prongs in each nest may be pressed with a projection 12a (see Fig. 2a) near its base to provide a stop thus to determine accurate spacing between the plane of the sheet 10 and the items 13 to be carried. Referring now to Fig. 3 which is a side view of the jig, in a subsequent step the sheet 10 is deformed step- wise as illustrated at 14a, 14b to cause the axes of the nests 11 to be disposed at an inclined attitude with respect to the general plane of the jig. The side edges of the sheet 10 are preferably provided with twisted tongues 15 (not shown in Figs. 1 and 2). Referring now to Fig. 4 in which, for ease of illustration, the prongs 12 have been omitted, the twisted tongues 15 project through elongate slots 16 in a pair of rigid side plates 17 which, together with the sheet 10, form a complete jig to be loaded into a carrier or frame cassette as will be described. Thus, the tongues 15 are twisted after passing through the apertures 16 to lock the sheet 10 and side plates 17 together as a rigid structure. At each end of each side plate 17 there is an enlarged part 18 containing an aperture 19 for a purpose to be described. The local end region 20 of the sheet 10 is welded to an end member 21 which has a semi-circular formation 22 coinciding with the aperture 19. Fig. 5 illustrates an entire jig 25 fully occupied by items to be anodised, all of the items being held at a uniform spacing and attitude to maximise production efficiency. Fig. 6 is an underside view of the complete jig 25 adapted to be loaded onto a frame cassette 23, but for ease of illustration the apertures left by the pressed out tongues have been omitted. Referring now to Fig. 7 there is shown a frame cassette 23 having upper and lower rows of outwardly projecting bars 24, coinciding upper and lower pairs thereof being adapted to support one of the loaded jigs 25. Thus, some twenty or more jigs may be mounted on each frame cassette 23 which, at its upper end, has location members 26 to be located on a flight bar being part of a transportation system carrying the frame cassettes 23 consecutively through the anodising and finishing process. Fig. 8 shows a jig 25 mounted on a frame bar 24 and carrying rows of items 13 to be treated. In Fig. 8 several rows of the sheet 10 and items 13 have been omitted for clarity. It will be seen in Fig. 6 that each side plate 17 of the jig includes a row of further apertures 27 to receive a mechanism being part of an automated system for loading the jigs onto the frame cassette. The provision of the semi-circular formed part 22 of the end member 21 welded to each sheet 10 ensures a firm electrical contact between the cassette and the frame bar 24 upon which it is located thus there is ensured a continuous electrical connection right through from the frame cassette 23 through the jigs and to each item 13 carried thereon. Fig. 8 also illustrates how the items 13 are carried at an axially-inclined attitude with their open ends lowermost to ensure drainage of liquids therefrom during the treatment procedure. Referring once again to Fig. 2, it will be seen that the geometrical arrangement of the nests 11 on the sheet 10 and the formation of the prongs 12 by linear piercing of the material from the sheet results in elongate apertures 30. These serve not only for the adequate flow of anodising liquids through the sheet but also provide spaces 31 through which may project stripping pins to enable the items to be stripped from the cassette simultaneously after completion of the anodising and finishing processes. For this purpose, trays similarly formed with pins aligned with the spaces 31 may be provided on a rigid sheet to which each jig is offered up in superimposed relationship to strip the items from the jig. Each frame cassette 23 is adapted to carry twenty or more jigs providing a total loading of some 9,000 items per frame. The inclined attitude of each nest is preferably some 15° from the general plane of the sheet 10 and the flat form pitch of the sheet produces equilateral triangular formations, the centres of the nests being approximately 24mm apart. After the stepwise deformation of the sheet as at 14a, 14b the pitch is compressed to some 19mm providing a finished size of sheet typically of 250mm by 900mm. The items are loaded preferably with their bases spaced 5mm from the face of the sheet and the jigs are preferably mounted in the frame cassette with the bars 24 pitched at 30mm spacing thus providing a minimum clearance between items on adjacent jigs of approximately 6mm. This is ideal for liquid flow and electrical purposes. Preferably, the frame cassettes 23 are automatically loaded onto a flight bar, three at a time, there being a locking mechanism to ensure firm contact between the flight bars and the cassettes whereby the latter are transported three at a time through the anodising process. The material of each sheet 10 and side plate 17 is preferably a titanium alloy or it may be an aluminium alloy depending upon the brightener solution used in the anodising process. Other materials may be possible according to their chemical resistance and electrical conductivity. Whilst the basic jig design will be constant, however the pitch configuration, prong design and stepwise deformation may change for different families of product at different diameter sizes. It will be appreciated that a jig made in accordance with the invention requires no maintenance and is of such construction and reduced cost that it may be considered as a disposable item after a period of use when the prongs 12 have perhaps become somewhat closed up thus not adequately to grip the items to be carried. Conceivably, a further jig may be provided with pins which may pass into the spaces between the upper ends of the prongs 12 to re-spread them and thus restore their resilience and resistance fit with the items to be carried. Several advantages accrue from a jig made in accordance with the invention including reduced manual handling of items to be anodised resulting in reduced or eliminated internal defects, the elimination of many manual activities involved in the preparation for, and after effect of, the anodising process thus resulting in a major increase in productivity. Such jigs are expected to result in a reduction of liquid carry over between the consecutive baths involved in the process thus reducing chemical contamination and consequent costs and failures. The jigs are also expected to provide much firmer electrical contact thus ensuring more consistent film thickness and uniformity of colour and surface finish of the items. In an alternative embodiment, the prong nests 12 may be individually attached to the surface of the sheet 10 by welding or conductive bonding, instead of being formed integrally by pressing as described above. In this case, the rear stepped face of the sheet 10 would appear plain as shown in Fig. 6.

Claims: CLAIMS 1. A jig for supporting and transporting hollow items through an anodising process, comprising an electrically conductive rigid sheet from at least one surface of which extends an array of nests of prongs upstanding from a planar surface of the sheet, each nest comprising two or more prongs mutually disposed and having sufficient resilience to retain a hollow item as a resistance fit thereon. 2. A jig according to Claim 1 , wherein the prongs are provided by piercing and deformation of the rigid sheet thus to be integral with and upstanding from the surface thereof. 3. A jig according to Claim 1 or Claim 2, wherein the planar surface of the sheet is stepwise formed such that the nests and prongs thereon are angularly displaced from the general plane of the sheet whereby the items may be held at an inclined attitude thereon. 4. A jig according to Claim 2 or Claim 3, wherein each nest of prongs comprises three angularly displaced prongs produced by piercing the sheet linearly about each nest and pressing the prongs upwardly therefrom. 5. A jig according to any preceding claim, wherein the prongs have inwardly curved tips to facilitate loading of the items thereon. 6. A jig according to any preceding claim, wherein each prong includes a projection in a base region to provide a stop whereby items may be placed on the jig at a predetermined distance from the general planar surface thereon. 7. A jig according to any preceding claim, wherein the nests of prongs are arranged in a geometric pattern with the nests of one row being offset laterally from the nests in the next adjacent row thus to maximise the number of items which may be carried on the jig with adequate spacing therebetween. 8. A jig according to any preceding claim, having sufficient nests to carry in excess of 400 items to be anodised. 9. A jig according to any preceding claim, including at least one rigid side plate attached by spaced projections along at least one side edge of the conductive rigid sheet. 10. A jig according to Claim 9, wherein the projections are provided in the form of tongues which pass through apertures in the side plate and are twisted to lock the sheet and the side plate together as a rigid structure. 11. A jig according to any preceding claim, having opposed end members adapted to locate upon spaced upper and lower bars of a frame cassette, the latter having location members whereby the cassette may be mounted on a flight bar being part of a transportation system to carry a number of frame cassettes through an anodising and finishing process, the end members of each jig providing electrically conductive contact between the jig and the frame cassette. 12. A jig according to any preceding claim, adapted when mounted on a frame cassette to carry items to be anodised at an axially inclined attitude with their open ends lowermost to ensure drainage of liquids therefrom during the anodising process. 13. A jig according to any preceding claim, wherein the sheet includes apertures adjacent the nests of prongs to receive stripping pins to remove anodised items simultaneously from the jig. 14. A jig according to Claim 1, wherein the nests of prongs are individually attached to at least one surface of the rigid sheet.

Inventors: BIGNELL NICHOLAS, BIGNELL, NICHOLAS
Applicants: BIGNELL NICHOLAS, DECORPART LTD, BIGNELL, NICHOLAS, DECORPART LIMITED
Application year: 1999
Main classification: C25D
IPC codes: C25D17