Plastic torsion spring

Could anyone give me any links to images/sites/existing products that show how a lid can pop/spring open about a pivot just using the
plastic parts themselves and not a metal torsion spring?
Any help would be much appreciated.
Thanks.
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Sggest you head on over to DuPont's Design & Processing page
http://plastics.dupont.com/myplastics/Mediator?id5&p=1&locale=en_US
and that you download document #7 "General Design Principles ... Module I"
http://plastics.dupont.com/plastics/pdflit/americas/general/H76838.pdf
In chapter 6, pages 36-37, you find lost of info on designing springs on Homo-POM.
This ought to get you started ...
will snipped-for-privacy@yahoo.co.uk wrote:

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On 26 Jun, 22:15, will snipped-for-privacy@yahoo.co.uk wrote:

Take a look at a plastic and aluminium letter plate in your local diy shop, for example Homebase or Wickes. I have one for my front door which consists of a plastic moulded frame - may be ABS - and an aluminium plate. The plate is retained shut by two torsion springs/pivot rods. These are around 1.5 ~ 2 mm diameter and about 50 mm long. They are injection moulded. One end has a 10 mm long lug which locates in a slot in the letter plate and the other end has a d-shape which is an interference fit in a d-shaped hole in the plastic frame. It worked very well - that is until my postie tried to deliver an overlarge item and busted it! I regret I don't know what the material of the torsion rod is. It is not a polyolefin, but other than that I cannot say. I suspect possibly nylon or acetal. Regards, Bill
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