Advancing material of indeterminate length – With adherence or attraction of material to advancing means – By pneumatic pressure
Patent
1997-02-26
1998-06-09
Mansen, Michael
Advancing material of indeterminate length
With adherence or attraction of material to advancing means
By pneumatic pressure
226170, B65H 2000
Patent
active
057622531
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a belt conveyor which includes an endless perforated belt having an upper and a lower run of which the upper run communicates with an underlying suction box along at least a part of its length.
BACKGROUND OF THE INVENTION
Such conveyors are often used in production lines in the manufacture of absorbent sanitary articles, such as diapers, sanitary napkins and incontinence guards, to support a web of material which, in the finished article, form the casing sheet of an article and onto which other components of the article, such as absorbent bodies, elastic devices, etc., are placed as the web passes the various stations located sequentially in the product line. Friction-driven belts having smooth top and bottom surfaces have been used in production lines of this kind. Belt conveyors of this kind, however, are encumbered with a number of drawbacks in the present context. One problem is that the belt often slips, i.e. moves at a different speed to the belt-drive roller or drum, which makes it difficult to move the belt at a precise and constant speed and therewith maintain a constant and specific distance between the mutually sequential operations in the production line. This phenomenon can sometimes result in serious disturbances in production. One contributory cause to belt-slipping is the ingress of dirt between the drive roller and the belt, this dirt causing slipping or variations in slipping induced by other factors. The slipping phenomenon also makes adjustment of the belt to its intended running speed at the start of production both difficult to achieve and time-consuming. The belt used in such conveyors is also liable to move sideways when in operation, which results in lateral misalignment of the components placed on the moving web of material. Another problem which is particularly accentuated in long conveyors is that the pressure difference generated by the suction box between the top and bottom runs of the belt causes the belt to curve downwards during operation, which is liable to impair precision in manufacture.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a belt conveyor which can be set to the desired belt-running speed readily and quickly and with which the belt will not slip so as to cause variations in the belt-running speed.
This object is achieved in accordance with the invention by means of a belt conveyor of the aforedescribed kind which is characterized in that the belt is driven by a cogwheel and includes ribs which extend transversely to the running direction of the belt and which coact with the cogs on the cogwheel and also with a cog drive on the conveyor. This enables the running speed of the belt to be set and controlled in a simple and reliable fashion, solely by adjusting and monitoring the cog drive or cog drives that drive the belt.
According to one preferred embodiment of the invention, the perforations in the belt also extend through the ribs in a pattern of longitudinally extending rows, and the ribs are recessed within the regions of the perforations so that the belt in these regions will have the same thickness as the belt in regions externally of the ribs. The upper belt run is supported by rails which extend generally along the full length of the run beneath each row of perforations, and which within the region of each suction box include upper openings which communicate with the belt perforations and lower openings which communicate with the interior of the suction box. The rails will preferably be made of a material which has good thermal conductivity, preferably bronze, and are coated on their upper surfaces with a wear-resistant layer of material which has small friction against the belt, preferably Teflon (registered trademark). The rails will preferably have a cross-sectional shape complementary to the recesses in the belt ribs, therewith preventing sideways movement of the belt. The rails preferably have a U-shaped cross-section presenting a bottom part and two upstanding legs.
REFERENCES:
patent: 3140030 (1964-07-01), Stewart
patent: 3425610 (1969-02-01), Stewart
patent: 3679112 (1972-07-01), Black et al.
patent: 3706406 (1972-12-01), Borel et al.
patent: 5595334 (1997-01-01), Belec et al.
.ANG.berg Kjell
Holt Roger
Mansen Michael
SCA Molnlycke AB
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