Surgery – Means and methods for collecting body fluids or waste material – Receptacle attached to or inserted within body to receive...
Patent
1994-11-30
1997-12-02
Clarke, Robert A.
Surgery
Means and methods for collecting body fluids or waste material
Receptacle attached to or inserted within body to receive...
215223, 215201, 215329, 206536, 264167, A61F 544, B65D 5502, D01D 520
Patent
active
056930364
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a method of moulding plastics articles, in particular to produce an article comprising an undercut formation on the inner surface of a cylinder, and to a novel plastics closure member and a novel plastics coupling element comprising such an undercut formation.
BACKGROUND ART
Moulding undercut formations, for example an internal flange around a circular lid or similar closure member, or around a ring coupling element, presents well known difficulties for injection moulding. The flange can be moulded by the use of an appropriately recessed core, but the radial extent of such a flange i.e. the amount of the undercut, must be relatively limited because of the need to extract the core from the moulding. Further, conventional techniques require the undercut to have a chamfered or sloped surface which can produce a camming action to stretch the moulding to get the flange past the mould core projection which formed it.
In moulding closure members and coupling elements from plastics materials, this need to have a chamfered or sloped surface can make the closure member or coupling element less secure and less positive, when for example, the closure member or coupling element is required to be a press fit over a lip on the external surface of a container or mating coupling element.
It has been proposed to produce undercut formations of the type described by injection moulding using a collapsing core, but in such cases the core leaves a so-called "witness line" on the moulded article, which is the imprint of the line between the movable parts of the collapsing core. In the case of a closure member or coupling element, this line can appear on the internal wall above the undercut and can severely limit the effectiveness of the seal made by the closure member or coupling element.
The invention aims to allow deeper undercuts which moreover do not need to be sloped, and to avoid the production of witness lines. A further object of the invention is to produce a novel closure member and a novel coupling element having a deeper undercut and a more secure closure and/or sealing action.
DISCLOSURE OF INVENTION
According to one aspect the present invention provides a method of injection moulding an undercut formation on a circular body, wherein said formation is moulded in a series of arcuate sections alternating with spaces, and wherein the moulding core which produces the formation is extracted by firstly relatively rotating said body and said core so that the body is expanded radially and then ejecting the body off the core.
The invention thus provides a method for forming moulded plastics article, and in particular a closure member or a coupling element, comprising an undercut formation on a circular body, said formation comprising a series of arcuate sections alternating with spaces, a plurality of the arcuate sections each having an undercut radially extending surface which subtends an angle to the axis of the body sufficient, in the case of a closure member or coupling element, to give a required degree of security to the article.
Certain closure members and coupling elements according to the invention are novel articles and are accordingly included within the invention.
Thus in a further aspect the invention provides a moulded plastics closure member comprising a circular body provided with an undercut formation, said formation comprising a series of arcuate sections alternating with spaces, ends of the respective arcuate sections being chamfered, the chamfered end surfaces of the arcuate sections being located at an angle of less than 60.degree. to a tangent to the circular body, and a plurality of the arcuate sections each having an undercut radially extending surface which is disposed at an angle to the rotational axis of the body sufficient to give a required degree of security to the closure member.
In this aspect of the invention the moulded plastics closure member preferably comprises a circular body having an undercut formation and a seal on an internal wall above
REFERENCES:
patent: 3339546 (1967-09-01), Chen
patent: 3782574 (1974-01-01), Rumble
patent: 4192785 (1980-03-01), Chen et al.
patent: 4257526 (1981-03-01), Weits et al.
patent: 4320230 (1982-03-01), Doyle
patent: 4393080 (1983-07-01), Pawelchak et al.
patent: 4551490 (1985-11-01), Doyle et al.
Clarke Robert A.
E. R. Squibb & Sons Inc.
LandOfFree
Method of injection moulding an undercut formation on a circular does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of injection moulding an undercut formation on a circular, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of injection moulding an undercut formation on a circular will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-797334