Return to index: [Subject] [Thread] [Date] [Author]

RE: Rolled Threads

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Mark-

	I agree that this is confusing. I think that one of the main issues
is that it is a common misconception that a bolt is the same animal as an
anchor rod. They do have many similarities, but there are enough differences
that it was suggested that the terminology be changed from anchor "bolt" to
anchor "rod". I think that this is an example of why.

	My understanding of the HS bolt manufacturing process is that the
bolt "blanks" as they exist before threading, have two body diameters. One
is the bolt shank (which is the final diameter of the unthreaded portion)
and the other section of lesser diameter is the portion where the threads
will be rolled. After the threads have been rolled, the major thread
diameter is nearly the same as the shank diameter.
	
	The larger shank diameter doesn't exist on an anchor rod "blank". It
is a rod of a single diameter. Therefore, for rolled threads, the body
diameter is in between the major and minor thread diameters.

	This geometry issue is hidden in A307. I think that B1.1 is a thread
spec and doesn't govern body diameter. IIRC, ANSI B18.2 is the geometry
spec. B18.2 is only referenced for A307 Grades A and B. I hadn't realized
this before, but B18.2 doesn't apply to anchor rods. Obviously, others have
realized this because F1554 specifies tolerances on the body diameter. You
may want to look at F1554 to get an idea of the rod diameters you are likely
to get with rolled threads.

HTH,

Heath



> -----Original Message-----
> From: Mark Gilligan [mailto:MarkKGilligan(--nospam--at)compuserve.com]
> Sent: Monday, March 25, 2002 9:04 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: Rolled Threads
>
> Nels
>
> I like you have relied on the representation of ANSI B1.1 in the steel
> manual.  It appears that they did not include some additional provisions
> which allow rolled threads.
>
> What I am hearing here is that  when rolled threads are used they start
> with a slightly smaller bolt diameter.
>
> By the way I believe that you are supporting my position that very few
> structural engineers have read ANSI B1.1.
>
> Mark Gilligan
>
>
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> The threaded fastener illustration on page 4-147 of the aisc 9th edition,
> or
> Table 7-4 of the aisc lrfd 3rd edition, refer to ANSI B1.1.  The 3rd
> edition
> shows the thread diameter to be db, which is noted to be the bolt
> diameter.
> Are you saying that there are bolts with bolt diameter that is defined by
> the diameter at the threads, but that have shanks that are of lesser
> diameter?
>
> Also, you seem to be saying that rolled threads will [or may] result in a
> bolt that has diameter at the threads greater than the diameter at the
> shank.  My understanding has been that rolled threads are applied to a rod
> by forming the threads into the round rod under pressure with no loss or
> addition of material, while cut threads are made by removing material, but
> that both procedures result in the same finish configuration.  Are you
> finding that this is not true?
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> *   This email was sent to you via Structural Engineers
> *   Association of Southern California (SEAOSC) server. To
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
> *   send to the list is public domain and may be re-posted
> *   without your permission. Make sure you visit our web
> *   site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ****** ********

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********