Plastic article or earthenware shaping or treating: apparatus – Diverse distinct type shaping means – Shaping orifice and either a downstream preform reshaping...
Patent
1990-02-15
1991-05-28
Hoag, Willard E.
Plastic article or earthenware shaping or treating: apparatus
Diverse distinct type shaping means
Shaping orifice and either a downstream preform reshaping...
425371, 425377, 425394, 425408, B29C 4726, B29C 9734, B29C 9322
Patent
active
050189590
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for producing grate constructions, comprising nozzle means for extruding plasticized material, and chill moulds moving one after another so as to define therebetween a moulding space after said nozzle means, the chill moulds travelling in the production direction within the area of the moulding space and comprising grooves on the mould surfaces facing the moulding space for forming ribs. As used herein, the term "grate construction" refers to constructions comprising elongated supporting means extending in parallel with each other, such as rods or tubes, and transverse ribs or the like interconnecting the supporting means. Constructions of this type are used widely, especially industrially, e.g., as working platforms in process industries. When the elongated means are tubes, the grate constructions can be used as heat exchangers or electrical heaters, whereby a heat storing medium or electrical resistors are placed in the tubes while the ribs form a large heat radiation surface. A ladder, too, is a kind of grate construction.
The production of grate constructions is slow and requires plenty of manual labour. The most usual practice is to manufacture the elongated means and ribs separately, whereafter they are possibly machined, and then interconnected by welding. This procedure limits the choice of materials as easily weldable and machinable materials only can be used, which causes problems with respect to corrosion resistance, for instance. Working platforms, for instance, cannot be made of chemically resistant plastic due to the technique used at the assembly stage.
The object of the present invention is to provide a device for the production of grate constructions at a single step. The device according to the invention is characterized in that the nozzle means comprise at least two adjacent nozzles, that the chill moulds form a moulding space at each nozzle, and that the moulding spaces communicate with each other by means of conduits formed in the chill moulds and connecting chill mould grooves surrounding adjacent moulding spaces with each other, for forming ribs extending from one elongated supporting means to be formed in the moulding space to another.
According to the invention, an extruder used in the production of ribbed pipes is modified in such a manner that the device can unexpectedly be used for continuously producing grate constructions, which increases the production rate, eliminates the need for manual labour and widens the choice of materials. The device according to the invention makes it possible to manufacture grate constructions of all extrudable materials, such as various plastics and metals and their mixtures, aluminium in particular.
In one embodiment of the device according to the invention, the grooves comprise, between the moulding spaces, at least one portion which is narrower than the rest of the groove. The produced construction can bend at this point, if desired.
By means of the device according to the invention, it is easy to manufacture constructions of greatly varying appearance, for aesthetic considerations, for instance. Thereby the device may be, e.g., such that grooves opening in adjacent moulding spaces are displaced with respect to each other in the longitudinal direction of the nozzles and the grooves communicate with each other through an interconnecting cavity for forming a thin material bridge.
In order to ensure that the material flows in adjacent moulding spaces join each other, the chill moulds may comprise means for heating them.
The invention is also concerned with a grate construction manufactured by means of the device, such as a heat exchanger or radiator comprising parallel tubular means and ribs transverse to the tubular means, the ribs being connected to and surrounding the tubular means. Prior art products are assembled of several parts interconnected by weld joints, for instance. Due to dimensional variations caused in the parts by production processes, the transferring of heat between the tubes and the ribs is not
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patent: 4690174 (1987-09-01), Jarvenkyla
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Hoag Willard E.
Uponor N.V.
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