Re: [CAD_CAM_EDM_DRO] Tubing Notcher

A couple of partners and I developed an in-house machine for the company
I work for in the mid-80's to do what you describe. We had to produce
large space frames fom T-1 tubing where the main members were 8" O.D and
the bracing members ranged from 8" down to 2" with as many as 8 members
intersecting at a node and up to 5 members in a given plane. Wall
thickness ranged from 1" to 1/4" and there were 15,000 or so ends to be
notched. The machine had one linear, two rotary axis and used an
oxy-fuel torch to cut the pipes. The linear axis was used to move the
torch parallel to the axis of the pipe being notched. One rotary axis
was used to rotate the pipe to develop the notch and the other was used
to tilt the torch to maintain a constant angle Vee-Groove for welding
between the notched pipe and the through pipe.

Programing was done using APT and the pipes were defined as cylinders in
space with each pipe having an ID cylinder and an OD Cylinder. Splines
were defined on each intersecting cylinder and the distance calculated
from a plane defined perpendiclular to the centerline of the cylinder
axis to the first intersection of the intersecting cylinder. The
intersection lengths from the ID cylinders were used to define a splined
curve that if wrapped around the pipe would define the intersection of
the pipe I.D. to the through pipe. These numbers were used to drive the
linear axis and notch the end of the pipe for the pipe ID intersection
as the first rotary axis rotated the pipe.

The intersection data from the OD splines was used to calculated the
instant angle formed by the end of the notched pipe to the through pipe.
For example for an 8" pipe intersecting and 8" pipe at 90 degrees, the
cut angle of the intersecting pipe is 90 at the deepest cut, 180 degrees
at the points of the notch and varies constantly in between. The welding
Vee -Groove angle was input into the program and subtracted from the
calculated cut angle. This angle was used to program the second rotary
axis.

The only thing else required was a manual axis mounted perpendiculat to
the linear axis. Since the notch is defined at the ID intersection to
the intersecting pipe, the pivot point of the second rotary axis must be
aligned and at the same radius as the ID of the pipe bing notched.

This worked quite well after a short period of debugging.

nitewatchman

douglasr987 wrote:

>I am interested in developing a tubing notcher based on CNC plasma
>cutting with a rotational and linear drive mechanism. Such a
>machine would be used to prepare pipes or tubes for joining (by
>welding) at various angles.
>
>There was some discussion of such a machine on this forum back in
>2000. (Refer message number 5920 and it's thread)
>Unfortunately, I am unable to contact Joe Vicars who started that
>thread and was developing a similar machine which he refers to as
>his R-theta tubing notcher. Joe's email address from this bulletin
>board is non-valid - does anyone know his current address?
>
>Since that posting back in 2000 there appears to have been no
>further discussion on this subject. My search for "notcher" returns
>no relevant results.
>
>The sort of machine that I am talking about can be seen at
>www.cypressweld.com/saddle.htm
>
>The intention is that the new machine to be developed will be more
>versatile and much cheaper than the available product from that
>company!
>
>I should much appreciate any guidance and ideas that anybody can
>offer. In particular, ideas for the system design and components
>that could be used.
>eg.,
>Rotary and linear drive mechanisms
>Workpiece holder (tube diameter will be a maximum of about 2in/ wall
>thickness 0.125in and maximum length of tubes about 6ft)
>
>It seems that the ultimate machine should offer control of the
>cutting angle relative to the surface of the tube to optimise the
>fit of the tubes for subsequent welding. Also, how should I control
>the plasma cutting torch stop/ start, gas supply etc.?
>
>I have a background in electronics so developing the machine control
>and software for the system should not be a great difficulty whilst
>the mechanical aspects of the machine will be more challenging for
>me. Nevertheless, I should also be interested to learn details of
>suggested electronic control systems and software that could be used
>in the implementation.
>
>Thanks in advance,
>
>Douglas Reid
>
>
>
>
>
>
>
>
>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@..., timg@...
>Moderator: pentam@... indigo_red@... davemucha@... [Moderators]
>URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
>OFF Topic POSTS: General Machining
>If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
>http://www.metalworking.com/news_servers.html
>
>http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
>
>NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
>bill
>List Mom
>List Owner
>
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>
>