Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Extrusion shaping means
Patent
1991-12-03
1993-06-15
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Extrusion shaping means
156363, 156555, 156566, 156573, 425145, 425148, 425166, 425363, B29C 6712, B29C 4702, B29C 4328
Patent
active
052195830
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND DISCUSSION
The invention relates to an apparatus for manufacturing a foil web of a thermoplastic with locally secured fittings for use as tarpaulins or similar articles, comprising an extruder head with an entirely or mainly downwards directed ejection orifice and two counterrotating rollers or similar members arranged below the ejection orifice, at least one of said rollers or members being cooled, said rollers or members forming between them a nip for calibrating the extruded foil, and a feeding device with an entirely or mainly vertical supply magazine for accomodating a stack of fittings, a discharge duct extending from the bottom of the supply magazine in a direction towards the roller nip and a guiding device for guiding the lowermost fitting in the magazine into the discharge duct.
An apparatus of this kind, which is used for example for the fastening of eyelets in a plastic foil web, which is subsequently to be cut in suitable lengths for production e.g. of tarpaulins for covering purposes in construction works is known from DK-published patent application No. 130 239.
In this prior art apparatus the guiding device formed as a reciprocating slide is driven by a hydraulic or pneumatical working cylinder and the discharged duct of the feeding device is arranged and designed in such a way that the supplied fittings are guided from the mouth of the duct towards the roller nip by the cooled roller.
Thereby, it is only possible to obtain a relatively inaccurate positioning of the fitting in the foil web, since the velocity with which the fittings are supplied from the mouth of the discharged duct is mainly determined by the stroke velocity of the slide.
The ejection of fittings may thereby in an unpredictable way take place at such a velocity, that the fittings strike holes in the soft foil web.
When a number of feeding devices arranged on a line in the axial direction of the rollers are used for fastening fittings along a corresponding line in the foil web in one operation, local differences in the surface character of the cooled roller has moreover led to a releatively inaccurate supply of the fittings of the roller nip.
Whereas these disadvantages have to a certain extent been acceptable in case of foil tarpaulins for singular use, they are not acceptable, when a greater number of tarpaulins are used for covering in construction works and arranged with overlapping edges since the said inaccuracies entail that the eyelets along the overlapping edges cannot be positioned opposite each other.
SUMMARY OF THE INVENTION
It is the object of the invention to provide an apparatus of the kind referred to, by which the said disadvantages are avoided so that the fittings are positioned with a great accuracy in the foil web and at a substantially higher working speed than has been possible in the above mentioned prior art apparatus, while at the same time a very high safety against malfunction, e.g. failing supply of fittings from one or more of a number of feeding devices, is obtained and thereby a considerable reduction of the rejection percentage.
To achieve this an apparatus according to the invention as characterized in that the guiding device is electrically operated and an electrically controlled stop member with an associated fitting sensing element are arranged in the vicinity of the lowermost end of the discharge duct towards the roller nip for accurate control of the supply of fittings to the roller nip and minitoring the presence of fittings in the discharge duct, the discharge duct being arranged in such a relationship to said counter rotating rollers that each fitting is supplied from the mouth of the discharge duct to the roller nip by a substantially free fall.
Thereby, in addition to a more accurate control of the movement per se of the guiding device, the advancement of fittings from the mouth of the discharge duct to the roller nip will be independent of the movement of the guiding device as well as the surface character of the roller and may thereby be controlled with a uniform a
REFERENCES:
patent: 3130106 (1964-04-01), Bornand
patent: 3219507 (1965-11-01), Penman
patent: 3671363 (1972-06-01), Bruder
patent: 3909340 (1975-09-01), Solbeck
patent: 4455188 (1984-06-01), Stormby
patent: 4502910 (1985-03-01), Voltmer et al.
patent: 4680080 (1987-07-01), Instance
Nguyen Khenh P.
Polysheet A/S
Woo Jay H.
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