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sectional thread

I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman

http://www.photoworks.com/photo-shar...&toh=&svr=web5

sectional thread

engineman wrote:

I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman

http://www.photoworks.com/photo-shar...&toh=&svr=web5

Because they used the same cap and bottle used in carbonated drinks. I'm taking a wild
arsed guess but the segments are to allow controled venting of pressure like when your
Pepsi is dropped from the top section of the vending machine, thus causing the carbonation
to get upset.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

sectional thread

On Sat, 21 Mar 2009 22:28:21 -0700 (PDT), the renowned engineman
wrote:

I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman

http://www.photoworks.com/photo-shar...&toh=&svr=web5

Can't see the photo without signing up.

So it had a break-off tamper indicator ring at the bottom of the cap?

Maybe to make it easier to push the cap onto the bottle.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

sectional thread

On Sat, 21 Mar 2009 22:28:21 -0700 (PDT), engineman
wrote:

I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman

http://www.photoworks.com/photo-shar...&toh=&svr=web5
==========
Mainly so the parts can be molded without the need for a special
"unscrewing" core.

By segmenting the threads it is possible to greatly simplify the
mold construction. It also eliminates the parting line problem
on the threads where the mold closes greatly reducing
maintenance.

Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).

sectional thread

On Mar 22, 9:00ï¿½am, F. George McDuffee gmcduf...@mcduffee-
associates.us wrote:
On Sat, 21 Mar 2009 22:28:21 -0700 (PDT), engineman

wrote:
I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman

http://www.photoworks.com/photo-shar...sionid=7ED5DB6....

==========
Mainly so the parts can be molded without the need for a special
"unscrewing" core. ï¿½

By segmenting the threads it is possible to greatly simplify the
mold construction. ï¿½It also eliminates the parting line problem
on the threads where the mold closes greatly reducing
maintenance.

Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).

I sent the wrong link- sorry, here's the right one:
http://www.photoworks.com/members/engineman

I don't think that these threads were designed for pressure relief,
they seem to be very strong.
The bottle seems to have 3 parting lines and the parting lines are all
on the lands of the thread.
Also it appears that the length and positioning of the lands would not
permit removal of the thread from the mold without unscrewing.
Engineman

sectional thread

On Sun, 22 Mar 2009 11:03:22 -0700 (PDT), engineman
wrote:

I don't think that these threads were designed for pressure relief,
they seem to be very strong.
The bottle seems to have 3 parting lines and the parting lines are all
on the lands of the thread.
Also it appears that the length and positioning of the lands would not
permit removal of the thread from the mold without unscrewing.

I think it's quite likely the threads are designed for fastest
handling by the molding and filling automation. In particular, the
blow molding machinery operates at very high rates. The preforms for
the blow molders are injection molded in multi-cavity molds, so the
cycle rates there are not too high. But I've seen blow molders running
at something like 20 bottles per *second*. These were continuous
motion machines, which means the preform, which looks like a little
capsule attached to a bottle neck and thread, have to be screwed into
a station on a carousel on the fly. The carousel on the fastest
machines I've seen were 8-10ft in diameter and spinning so fast the
individual stations were a blur. That interrupted thread would allow
the preform to be mated up in a fraction of a turn rather than the
couple turns required to remove the cap.

An animation of a single station:
http://www.youtube.com/watch?v=vSabFFQUr9E

There's a continuous motion blow molder in the middle of this video,
but it's only running at 3 bottles/second.
http://www.youtube.com/watch?v=T01i_vp2mJE

--
Ned Simmons

sectional thread

On Sun, 22 Mar 2009 14:54:04 -0500, the renowned Bert
wrote:

engineman wrote:
On Mar 22, 9:00?am, F. George McDuffee gmcduf...@mcduffee-
associates.us wrote:
On Sat, 21 Mar 2009 22:28:21 -0700 (PDT), engineman

wrote:
I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman
http://www.photoworks.com/photo-shar...sionid=7ED5DB6...
==========
Mainly so the parts can be molded without the need for a special
"unscrewing" core. ?

By segmenting the threads it is possible to greatly simplify the
mold construction. ?It also eliminates the parting line problem
on the threads where the mold closes greatly reducing
maintenance.

Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).

I sent the wrong link- sorry, here's the right one:
http://www.photoworks.com/members/engineman

I don't think that these threads were designed for pressure relief,
they seem to be very strong.
The bottle seems to have 3 parting lines and the parting lines are all
on the lands of the thread.
Also it appears that the length and positioning of the lands would not
permit removal of the thread from the mold without unscrewing.
Engineman

It is so the cap does not go flying off from the pressure.

Google Patent number: 4747502, plus there are a few others.

MikeB

Eg. 6234338

Bingo! So as you unscrew the cap, the pressure can vent safely out
through the slots, whilst the cap is safely contained on the bottle
threads.

The security ring is screwed on with the cap-- just it has fingers
that snap out into a groove in the neck and retain it, with far more
strength than the bits that get torn when the cap is removed. I think
I could make a tool to remove Dansani security caps without breaking
them.

Thanks for this question-- I actually have taken a course in design of
blow molds and this area was not covered (though there was endless
discussion of 'starts' and such like). The standard thread forms are
covered by a part of the SPI- the Plastic Bottle Institute, believe it
or not.

http://tinyurl.com/dl9nw4

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

sectional thread

I guess photoworks is a private user only site. Strange to be photo-sharing...
Said I had to log in with username and password.
Martin

Spehro Pefhany wrote:
On Sat, 21 Mar 2009 22:28:21 -0700 (PDT), the renowned engineman
wrote:

I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman

http://www.photoworks.com/photo-shar...&toh=&svr=web5

Can't see the photo without signing up.

So it had a break-off tamper indicator ring at the bottom of the cap?

Maybe to make it easier to push the cap onto the bottle.

Best regards,
Spehro Pefhany

sectional thread

Da - just thought of the reason - we all had it right - but think:

If the bottle is high pressured - and you un-screw it - you want to
vent the gas and liquid without blowing the top into someones eye
or the like. e.g. wet hands but not broken eye cornea.

Martin

engineman wrote:
On Mar 22, 9:00ï¿½am, F. George McDuffee gmcduf...@mcduffee-
associates.us wrote:
On Sat, 21 Mar 2009 22:28:21 -0700 (PDT), engineman

wrote:
I have a plastic bottle that once held Lipton's green tea.
when I looked at the threads on the bottle it looks like they consist
of segments.
The cap has similar threads.
I'm wondering what the reason for these strange threads?
Engineman
http://www.photoworks.com/photo-shar...sionid=7ED5DB6...
==========
Mainly so the parts can be molded without the need for a special
"unscrewing" core. ï¿½

By segmenting the threads it is possible to greatly simplify the
mold construction. ï¿½It also eliminates the parting line problem
on the threads where the mold closes greatly reducing
maintenance.

Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).

I sent the wrong link- sorry, here's the right one:
http://www.photoworks.com/members/engineman

I don't think that these threads were designed for pressure relief,
they seem to be very strong.
The bottle seems to have 3 parting lines and the parting lines are all
on the lands of the thread.
Also it appears that the length and positioning of the lands would not
permit removal of the thread from the mold without unscrewing.
Engineman

sectional thread

Spehro Pefhany writes:

The standard thread forms are
covered by a part of the SPI- the Plastic Bottle Institute, believe it
or not.

For years I've desperately wanted specifications for these threads. Where
are they to be found? Can you bless me with them?

sectional thread

On Mar 23, 6:16*am, Richard J Kinch wrote:
Spehro Pefhany writes:
The standard thread forms are
covered by a part of the SPI- the Plastic Bottle Institute, believe it
or not.

For years I've desperately wanted specifications for these threads. *Where
are they to be found? *Can you bless me with them?

Does this help - it has been a book mark of mine for a while
http://www.kenplas.com/topic/neckfinish/

regards
Tim
South Africa