Conveyors: fluid current – Having means for maintaining load in suspension along flow path – By load supporting jets
Reexamination Certificate
2000-02-25
2002-12-03
Ellis, Christopher P. (Department: 3651)
Conveyors: fluid current
Having means for maintaining load in suspension along flow path
By load supporting jets
C198S466100, C198S465400, C406S087000
Reexamination Certificate
active
06488449
ABSTRACT:
RELATED APPLICATIONS
Foreign priority benefits are claimed under 35 U.S.C. § 119(a)-(d) or 35 U.S.C. § 365(b) from French Patent Application Serial No. 97/10770 filed Aug. 25, 1997, and under 35 U.S.C. § 365(a) from PCT International Application PCT/FR98/01646 filed Jul. 24, 1998, which designated at least one country other than the United States. PCT Application PCT/FR98/01646 of which this application is a National Stage filing under 35 U.S.C. § 371, was published under PCT article 21(2) in French.
BACKGROUND OF THE INVENTION
The Present/invention relates to conveying articles having a collar or the like projecting therefrom and enabling them to be suspended while they are being transported. The invention relates more particularly to a conveyor in which the articles are transported while being suspended from their collars resting on two under-neck guides acting as guide rails, and being more particularly propelled one behind another by means of a flow of air. A main application of the invention lies in transporting lightweight articles made of plastics, such as receptacles (pots, bottles, etc.) made of PET, PVC, etc . . . , in particular during packaging operations involving these articles, the conveyor being used, for example, to bring a line of empty receptacles from an upstream machine for manufacturing the receptacles (a blow-molding machining) to a downstream machine for filling the receptacles (a bottling machine).
In the field of bottling, it is now a widespread practice to use pneumatic conveyors in which empty bottles, or more generally articles, are guided one behind another between two under-neck guides while being supported by means of respective projections from their necks (the collars). The articles are set into motion individually one behind another or else in entire trains of bottles, under drive from jets of air. Such conveyors have already been described, for example, in international patent application WO 90/10587, and in British patent application GB 2 092 981. In those two publications, the driving airjets are directed mainly on the necks of the articles above their collars. In other types of known conveyors, the driving air jets can also be directed onto the bodies of the articles below their collars.
While they are being transported, the articles which are supported solely by their collars have a tendency to swing relative to the vertical. Receptacles swinging relative to the vertical in a direction that is transverse to their travel direction become difficult to convey and also give rise to risk of the articles being dropped or else becoming jammed. Proposals have therefore already been made to limit such swinging in a direction that is transverse to the travel direction by fitting conveyors with lateral guides positioned on either side of the article transport path. In practice, such lateral guides are positioned level with the cylindrical body portions of the articles and they are spaced apart from each other by a distance that is slightly greater than the diameter of said cylindrical portions. The articles are thus supported by their collars and while they are being transported they are held essentially vertically by the guides in respective vertical planes that extend transversely to the transport direction. However, the above-mentioned guides are not sufficient to ensure that the articles are conveyed properly. In particular, such guides do not prevent the articles from jamming while they are traveling.
In practice, while the articles are being conveyed, jamming occurs most frequently while articles are being accumulated, i.e. during stages in which the articles build up into a train that is stationary or moving very slowly, with the articles coming into contact and being pressed against one another.
Such jamming of articles during an accumulation stage can have various causes. In general, while the articles are pressed against one another they exert thrust which tends to lift them vertically off the under-neck guides. Under such circumstances, it can happen that at least one of the articles, because it has been lifted vertically, becomes jammed in position by wedging between the under-neck guides. It can also happen, when articles are of a profile which contributes to enabling them to be interfitted relative to one another, that in the event of an article being lifted vertically, the articles jam relative to one another without necessarily jamming by becoming wedged between the under-neck guides. It has also been observed that the risk of jamming is higher when transporting plastic articles, and in particular PET bottles, that have come directly from a blow-molding machine. This can be explained by the fact that the thermoplastic resin constituting the walls of the plastic articles coming from a blow-molding machine is in a state such that the walls of the articles are sticky, and the mere fact of one article rubbing against another while articles are being lifted can lead to the articles sticking together. Another cause of articles jamming during an accumulation stage is associated with the fact that an article coming into contact at speed with a train of accumulated articles tends to tilt significantly relative to the travel direction by bearing against the last article in the accumulated train. If the next article arrives at this particular moment and presses against the base of the article that is tilted in the travel direction, it exerts mechanical thrust thereon tending to lift it between the under-neck guides and to jam it in the tilted position.
Proposals have already been made in U.S. Pat. No. 5,421,678, to fit an air conveyor with tope guide-shoulders (referenced
42
in
FIGS. 4
,
7
, and
8
of that document) whose main function is to act as an abutment in the event of an article being lifted. That solution nevertheless presents the following two major drawbacks. With that solution, the problem of receptacles jamming between the under-neck guides is indeed reduced, however a new risk arises of the receptacles jamming between the guide-shoulders, in particular when receptacles are lifted during an accumulation stage. That solution is therefore not satisfactory with regard to the problem of articles jamming during an accumulation stage. The other drawback of that solution is associated with the problem of determining the optimum setting for the spacing between the guide-shoulders. By acting on the spacing between the guide-shoulders, the distance through which the articles can be lifted can be increased or reduced. In practice, the closer together the guide-shoulders, the better the prevention of vertical jamming of the articles. However, by acting on the spacing between the guide-shoulders, the forward or backward tilt angle in a vertical plane of the articles in their travel direction is also varied. In practice, the smaller the spacing between the guide-shoulders, the more narrowly the tilt angle of the articles is limited. Although it is known that an excessive tilt angle of the articles while they are being conveyed can give rise to the articles jamming forwards or backwards relative to the under-neck guides, it is nevertheless necessary for articles that are being conveyed to be capable of oscillating slightly relative to the vertical in the transport direction through some minimum tilt angle so as to obtain better conveyability of the articles. With the top guide-shoulder solution of U.S. Pat. No. 5,421,678, it is thus necessary to adjust the spacing between the guide-shoulders as a function of two constraints: providing an effective abutment against the articles being lifted; and putting a proper limit on the forward or backward tilt angle of articles while they are being conveyed. Those two constraints make it difficult to achieve an optimum setting for the spacing of the guide-shoulders.
SUMMARY OF THE INVENTION
The present invention proposes a novel solution serving to reduce the risk of articles jamming, in particular during an accumulation stage, while mitigating the two above-mentioned drawbacks inherent to implementin
Blanchet Gilles
Declercq Philippe
Laquay Fabien
Meunier Jean-Luc
Travail Bruno
Ellis Christopher P.
Netra Systems
Sharma Rashmi
Wolf Greenfield & Sacks P.C.
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