JIG CLEANING

Abstract: An apparatus and method for removing surface coating of an article carrying jig (11) so as to enable electrical contact between the jig and the or each article (12) to enable the articles to be coated with surface coating in a treatment chamber wherein the surface coating on the jig is removed by subjecting the jig and article to vibration so that the resulting movement between the articles and the jig abrades the surface coating on the jig hence enabling electrical contact between the jig and the articles.

Description: Title: JIG CLEANING Description of Invention The present invention relates to apparatus for coating articles and primarily, but not exclusively to apparatus for coating metal articles by dipping, spraying, powder coating, and similar processes to coat the surface of an article with a non conductive surface covering to form a protective coating on the article. In order that each of the articles are properly coated they are suspended or otherwise attached to a jig and moved into a treatment chamber in which they are coated. It is normal for such jigs to hold a large number of articles which are kept separate from each other but in close proximity so as to enable the treatment of a maximum number of articles at any one time. In processes which require the passing of an electrical current through the article it is necessary to have a good electrical contact between the jig and the article suspended thereby, when the jig is new and the article is clean this provides no problem. However once the jig has been used, since necessarily the current passes through the jig and through the article, it will be appreciated that not only is the article coated with a protective layer but also the jig will be similarly coated. Once the articles have been treated it is necessary to clean the jig and one method of cleaning include heat treatment of the jig to melt the coating which may then be brushed off for example by wire brushes. If the jig was subjected to high temperatures this might in itself be sufficient to burn off the coating. However, since the jigs are made from metal, necessary for the conduction of electricity, excessive heat treatment will distort the jig and after a few treatments not only can distortion take place but the metal can become unduly tempered and insufficiently rigid to support the articles. The cleaning of such jigs takes a considerable length of time and in order to make efficient use of the apparatus it is necessary to have a large number of jigs so that there are a sufficient number for a continuous throughput of clean jigs on which articles may be loaded. It is an object of the present invention to provide a new or improved method of removing surface coating from a jig. According to one aspect of the present invention we provide an apparatus for removing surface coating material from a jig adapted to carry one or more articles, said apparatus including vibration means adapted to vibrate the jig and cause relative movement between the jig and the or each article carried thereby such movement causing removal of sufficient surface coating from the jig to enable an electrical connection between the jig and the article. Conveniently said vibration means may be provided in a part of a coating apparatus adapted to lift and/or convey a jig loaded with articles to be coated towards a treatment bath. Preferably said vibrating means is provided on a jig support so that when the jig is supported and having already been loaded with articles to be treated it is vibrated causing relative movement between the articles and the jig which relative movement causes the surface coating on the jig to be removed in the area of contact between the jig and the articles supported thereby. The frequency and the amplitude of vibration may be varied depending on the weight of the articles and the materials from which they are made and the length of time for which they are subject to vibration may also be altered depending on the criteria of removing sufficient surface coating from the jig to enable satisfactory electrical contact between the jig and the articles supported thereby. The above described apparatus for removing surface coating from a jig is a considerable improvement of known jig cleaning techniques particularly, when the vibration means can be incorporated in an automatic conveying apparatus since the hitherto necessary step of removing the jig from the treatment path and subjecting it to prolonged heat treatment, followed by mechanical cleaning can be avoided. Once the articles have been treated and dried they may be removed from the jig, the jig may then be reloaded with new untreated articles and the jig and articles supported thereto subjected to vibration in their conveyed path from a loading area a treatment area. The automatic conveying apparatus may be an indexing conveyor arranged such so that there is movement along a conveying path for a period of time followed by a non movement time. Conveniently the non movement time may be used to subject the jig and articles to vibration. It is further envisaged that the jig and the articles may be subjected to two vibration treatments possibly, at different amplitudes, different frequency of vibration and for a different frequency of time. It is also envisaged that additional, or alternatively, the articles may be subjected to vibration whilst they are being moved along the conveying path. According to another aspect of the present invention we provide a method of removing surface coating for an article supporting jig comprising loading one or more articles to be treated on the jig and subjecting the jig to vibration to cause relative movement between the articles and the jig to abrade or otherwise remove surface coating on the jig in the area of contact between the jig and the or each article supported thereby. It will be appreciated that the above mentioned apparatus for and method of removing surface coating from a jig is suitable for any treatment plant in which it is necessary for electrical conduction between the articles to be treated and a jig supporting said articles. The invention will now be described in more detail by way of example only with reference to the accompanying drawings wherein: FIGURE 1 is view of part of a jig with an article supported thereby. FIGURE la is a further view of a support bar FIGURE 2 is a detailed view showing the area of contact between the jig and the article. FIGURE 3 illustrates a complete jig with articles supported therefrom on a conveying means and, FIGURE 4 illustrates a vibrating apparatus supporting jig carrying bars. FIGURE 5 is a schematic illustration of a treatment system. Referring first to Figures 1 and 2, Figure 1 illustrates a support rod 10 to which is secured a plurality of hooks such as those shown at 11. In reality the bars 10 may be of considerable length for example at least 1 metre and a large number of hooks 11 will be secured thereto, each of the hooks 11 being adapted to support an article such as the article shown at 12. The article 12 may, for example, be a metal pressing which it is required to coat with paint to provide not only a protective coating to the article 12 but also possibly to improve its appearance. The jig of which the support bar 10 and hooks 11 comprise a part has already been used and hence is coated with paint which will prevent , electrical contact between the article 12 and the hook 11. In order to clean the jig, at least in the area of contact between the article 12 and the hook 11, the complete jig is vibrated by a vibrating device, the amplitude and frequency of the vibration being determined, at least in part, by the weight of the article 12 and the material from which it is made. Vibration will cause relative movement of the article 12 in the hook 11 and the edges of the part of the article 12 in contact with the hook 11 will cause abrasion of the surface coating until metal to metal contact is possible. Referring in addition to Figure la, it can be seen that the support bar 10 has a bent end region 10a which locates on a V shaped support 22 which can also been send in Figure 3. The bent portion 10a not only helps to locate the support bar 10 on the jig but also is inclined so that the hooks 11 project forwardly. This helps to maintain the articles 12, particularly when light in weight, from falling off the hooks 11. Figure 2 shows an enlarged view of the hook 11 and the article 12 and the areas 15 on the hook 11 are contacted by the edge areas 16 on the article 12 and after vibration the cleaning of the hook 11 can be seen. It has been found in practice that a vibration time of approximately two to six minutes has been found effective to clean the hooks 11 sufficiently to provide electrical contact between articles 12 and the hooks 11. Referring in addition to Figure 3 and 4, Figure 3 shows a complete jig 20 which is provided with a plurality of bars 21 secured thereto, the bars having V shaped separating structures 22 and between which bars 21 can be supported the support bar 10. It can be seen from Figure 3 that a large number of support bars 10 may be provided on a single jig thereby enabling a large number of articles 12 to be treated at the same time. The jig 20 is suspended from a pair of carrier bars 25 which have a pair of T bars 27 which can be engaged or disengaged with a carrier member 24 which is moved along a conveyor track 26. The T bar connection 27 and carrier 24 enable the conveyor system to pick up the jig 20 and deposit it at any one of a different number of stations. Referring now in addition to Figure 4 the upper part of a vibrating station is shown. The vibrating station has a pair of spaced support members 28, one of which is shown, supporting the ends of the two carrier bars 25. It will be appreciated that there will be another support member 28 to support the other ends of the carrier bars 25. It is further envisaged that the carrier bars 25 maybe provided with transverse members and it is possible that the ends of the transverse members can be supported by the support member 28 so that the jig is supported from its sides rather than at each end. The vibrating station will necessarily have a substantial height so that the jig is freely supported from the upper end thereof and a vibrating means 29 having a power lead 30 is shown attached to the support member 28 so that the vibration from the vibrating means 29 is transmitted through the support member 28 carrier bars 25 to the entire jig. In order that the vibrating energy is dissipated to the jig and not to the vibrating station itself rubber insulating blocks 30 support the support member 28 from the base 32. Energisation of the vibrating means will vibrate the entire jig thus causing relative movement between the articles 12 suspended from the hooks 11 which in turn causes abrasion of the hooks 11 removing surface coating from the hooks 11 due to abrasive contact with the articles themselves. The type of abrasion caused to the surface coating on the hooks 11 is shown in Figure 2. The vibrating means 29 maybe electrically powered as shown in Figure 4 or if the apparatus is situated in an hazardous area it may be pneumatic hydraulic. It is envisaged that control means may be provided to alter the frequency of vibration, the amplitude of vibration and furthermore timing means maybe provided so that a set time can be given for vibration to take place to produce the desired removal of surface coating from the hooks 11 without causing wear to the hooks themselves. It is envisaged for example, where the vibrating means 29 comprised a rotating eccentric the eccentricity can be increased or decreased whereby increasing or decreasing the amplitude of vibration, the speed of rotation may be increased or decreased thereby altering the frequency of vibration. It will be appreciated that in order to produce the desired effect, the nature of the articles being and their weight and material may dictate different vibration speeds and amplitude. It is further envisaged that more than one vibrating station maybe provided and furthermore, in alternative systems the articles maybe vibrated on a jig during movement along the conveying means. Where there is any vibration of the jig during movement of the conveying means it will be appreciated that the carrier member that supports the carrier bars 25 will be well insulated by rubber mountings for example to prevent the vibration being transmitted to the conveying means 26. In the case where the articles to be treated are metal pressings and are supported by passing the hooks through a through bore, the through bore is likely to have relatively sharp edges which contributes significantly to the ability of the relative movement between the article 12 and the hook 11 to cause erosion of the surface material provided on the hook 11 of the jig 20. Vibration of the jig for a pre-determined length of time will be sufficient to ensure that there is adequate electrical connection between each of the articles 12 suspended from the hooks 11 of the jig 20 for a current to pass there through and enable the treatment to be carried out successfully. Referring now in addition to Figure 5 a systematic view of a treatment system is illustrated and 26 indicates the conveying path. A first treatment bath is shown at 35 in which the jigs are immersed and is normally provided with a cleaning fluid so that the articles to be plated are de-greased or otherwise cleaned. Further treatment baths are shown at 36 and 37 which may comprise the surface coating treatment and the jigs are then removed by the conveying means 26 having a drying station 38. An unloading and loading station is shown at 39 where the jigs maybe removed from the conveying system so that operatives may unload the articles that have been plated and reload the jigs with articles to be treated. It will be appreciated that at this time the bars for supporting the articles will have been coated with surface material in the baths 36 and 37 and they are then moved to a vibrating station 40 so that prior to immersion in the treatment baths electrical contact between the articles to be plated and the jig is possible thus the current passing through the jig and through the treatment bar enables the articles to be provided with a surface coating. The apparatus and method of the present invention provides a very considerable improvement of the process as a whole by providing a simple and very efficient manner of cleaning the jigs and also obviously the need for a large number of extra jigs to be made. Furthermore, particularly when the vibration means is activated whilst the jigs are being conveyed from a loading bay, to a surface treatment bath the extra time taken to clean the jig compared with the process as a whole may be negligible. A still further advantage of the present invention is that because the paint or other material does not have to be removed from the remainder of the ig since, the relative vibration between the jig and the articles cleans only the area of contact between the article and the jig. When the jig and the articles are submerged in the treatment bath surface coating is applied only to the articles since the jig will already be coated with surface coating, from the area of contact with the article with paint or other surface coating. This results in a considerable saving in the surface coating material. It will be appreciated that the apparatus shown is merely an example of how the invention can be put into effect and the vibration means may be sited anywhere that is suitable providing it is capable of causing relative movement between the jig and the article supported thereby sufficient to cause removal of part of the surface coating on the jig. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS 1. Apparatus for removing surface coating material from a jig adapted to carry one or more articles, said apparatus including vibration means adapted to vibrate the jig and cause relative movement between the jig and the or each article carried thereby such movement causing removal of sufficient surface coating from the jig to enable an electrical connection between the jig and the article. 2. Apparatus as claimed in Claim 1 wherein said vibration means is incorporated in part of a conveying apparatus adapted to lift and/or convey said ig towards a surface coating treatment chamber. 3. Apparatus as claimed in Claim 2 wherein said treatment chamber comprises a bath having said surface material contained therein. 4. Apparatus as claimed in any one of claims 1 to 3 wherein said vibrating means is provided on a jig support apparatus positioned before a treatment chamber so that the jig and articles may be vibrated prior to entering said treatment chamber. 5. Apparatus as claimed in any one of the preceding claims wherein said vibrating means is operative to remove said surface coating from said jig only in the area of contact between said jig and the or each article. 6. Apparatus as claimed in any one of the preceding claims wherein means are provided to alter the length of time for which the jig is vibrated. 7. Apparatus as claimed in any one of the preceding claims wherein means are provided to alter the amplitude of vibration. 8. Apparatus as claimed in any one of the preceding claims wherein means are provided to alter the frequency of the vibration. 9. Apparatus as claimed in any one of the preceding claims further comprising one or more treatment chambers, a drying chamber, a vibrating station and an article loading and unloading station and conveying means adapted to move an article carrying jig between said chambers and said stations. 10. Apparatus as claimed in any one of the preceding claims wherein said ig comprises a plurality of threaded bars each bar carrying a plurality of hooks secured thereto, said hooks being adapted to support said articles. 11. A method of removing surface coating from an article supporting jig comprising loading one or more articles to be treated in a treatment chamber on the jig and subjecting the jib to vibration to cause relative movement between the articles and the jig to abrade or otherwise remove the surface coating from the jig in the area of contact between the jig and the or each article carried thereby. 12. A method as claimed in Claim 11 wherein said method further comprises supporting said jig at a vibrating station causing vibration to be carried out prior to moving said jig and said articles to a treatment chamber. 13. A method as claimed in Claim 11 or Claim 12 wherein said jig is vibrated for at least two minutes. 14. A method as claimed in Claim 13 wherein said jig is vibrated for at least five minutes. 15. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 16. A method of removing surface coating from an article supporting jig substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 17. Apparatus including an novel feature or novel combination of features as disclosed herein and/or illustrated in the accompanying drawings. 18. A method of removing surface coating from a jig including any novel feature or novel combination of features as described herein and/or illustrated in the accompanying drawings.

Inventors: SMITH PETER JOHN, SMITH, PETER, JOHN
Applicants: PROTECTIVE FINISHING GROUP LIM, SMITH PETER JOHN, PROTECTIVE FINISHING GROUP LIMITED, SMITH, PETER, JOHN
Application year: 2000
Main classification: B05B5
IPC codes: B05B5, C25D17