Re: [CAD_CAM_EDM_DRO] Making a punch die?

Hi,

Just a thought on this - how are you intending to hold the punch and die
while using them? Most of the simple 'chassis punches' use an allen screw
through a pre-drilled hole to pull the two parts together but this would not
be very convenient for a DB25 shaped punch because of alignment problems
between the two halves. I suppose there would be a chance if you used two
allen screws towards the ends of the die but would you be able to use strong
enough screws to withstand the forces needed to drag the whole length of the
side cuts through the aluminium. At the very least you would need to shape
the bottom of the punch so that the cut is progressive i.e. it starts at the
middle and finishes at the ends or vice versa.
More commonly, a punch of this size would be used in a fly press (screw
press) where the massive construction of the press body would allow a big
enough throat depth to manouvre the metal beneath the punch. Accurate
alignment of the punch and die will still be an important issue and it would
be good practice to make the punch and die as a sub-press assembly i.e. two
substantial metal plates with locating posts and separating springs (and
often a sprung stripper plate) with the punch mounted on one and the die on
the other. This is placed as a unit under the press.

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk

----- Original Message -----
From: "Spehro Pefhany" <speff@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 12 July 2001 23:47
Subject: Re: [CAD_CAM_EDM_DRO] Making a punch die?


> At 08:03 PM 7/12/01 -0000, you wrote:
> >Hi,
> >I'd like to make my own punch dies for cutting cutouts for electronic
> >connectors in an aluminum case (0.062). Has anyone tried this or
> >seen information that might help?
> >Joseph
>
> My reference says for 1100/5052 aluminum clearance of 4.5% of material
> thickness
> for 2024 and 6061 alum. clearance of 6% of material thickness for punching
> and blanking,
> so 2.75-3.5 thou clearance (per side).
>
> Punch force in lb. should be S(psi) * circumference (in)* thickness (in)
>
> Eg. if the circumference is 3", and the shear strength of the material
> (2024-T4 alum)
> is 41,000 psi, then it would be 41,000 * 3" * 0.062 = 7626 lb.
>
> Stripping force in tons = length of cut (in) * material thickness (in) *
1.5
> in the above example = 0.28 ton.
>
> Source: Die Design Handbook (SME publication)
>
> Best regards,
>
>
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=
> Spehro Pefhany --"it's the network..." "The Journey is the
reward"
> speff@... Info for manufacturers:
http://www.trexon.com
> Embedded software/hardware/analog Info for designers:
http://www.speff.com
> Contributions invited->The AVR-gcc FAQ is at:
http://www.bluecollarlinux.com
>
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
=
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>
> Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> Moderator: jmelson@... timg@... [Moderator]
> URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> bill,
> List Manager
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>