Description of Process

COPRAź
for Drawing Rings - 2D Part  (M5)
and
COPRAź for Drawing Rings - 3D Part (M6)

Example of a drawing ring

Example of a drawing ring

 

COPRAź Drawn Tube Technology - Calculating the shaping process for drawn tubes
For the manufacturing of drawn tubes round tubes are pulled through one or more drawing rings depending on the complexity of the final shape. The drawing rings are approximately between 40 and 100 mm thick. The incoming side needs to be large enough to cover the round tube. The outgoing side has the final shape of the tube or a defined pre-shape. The faces between the incoming side and the outgoing side build a curve. Of course it would be easier if the two contours (round tube and final shape) would be connected with straight lines. But in this case the friction between tube and drawing ring gets too high and causes other problems.
Especially the design of the outgoing shape of the drawing ring is not trivial because the straight legs of the final shape needs to be converted into arcs. It has been nearly impossible to do a true design keeping the circumference of the tube only with the help of a drawing board. Design as well as manufacturing of drawing rings has been quite difficult up to now.

The design of drawing rings has been characterized by following difficulties.
The layout of the drawing ring was mostly made free hand.
The length of the individual lines was very hard to estimate.

The manufacturing of drawing rings has been making difficulties as well.
The shape of the incoming tube, for example, was made with a machining tool which had mostly the same contour.
The manufacturing process itself was very long and winded
A negative had to be made from the outgoing contour and the shape of the
machining tool.
The negative had to be casted to get an original part.
This part was manufactured with a copy mill. It also had to be reworked in order to remove intersections with the incoming tube.

Therefore a CAD/CAM system for the design and manufacture of drawing rings should allow
an easy design of the drawing ring shape,
a high accuracy material flow,
an easy machining of the drawing ring.
It should avoid additional intermediate steps like the need to machine a negative and it should provide the possibility to design and manufacture additional tools required, like cores etc.

 

COPRA for Drawn Tubes is the only software available for this specific problem. Its data model is compatible with the COPRA Roll Form Software and uses Mechanical Desktop by Autodesk for the surface modeling and an industry standard NC programming system like AlphaCAM by Licom Systems for the NC-code generation. These components build a complete process chain covering all steps of the design and manufacturing process.

The design process is done in the following steps:
1) design of the final section
In the first step the final section needs to be designed. This can be done with the features provided by COPRA or by using the basic CAD-system. In this case the outside contour of the section will be designed with CAD-functions and then its data will be converted for the use with COPRA.
2) design of individual shaping steps
This is the most important - and also most difficult - step in the process chain. The shape of the drawing ring is determined by a number of sections through the ring. How many shapes will be used to create the drawing ring geometry can be user-defined. Beyond that a compression factor can be defined for each individual section of the drawing ring. With this option it is possible to get the necessary curvature.

With these information the computer program will calculate the individual sections as selected. As COPRA does know the individual position of any arc at any time it can make sure that the material flow of the shaping process will be an optimum. It may not happen that the length of an arc is too short or too long as it used to happen during a design on the drawing board.
The result supplied by the program are closed shapes (poly lines) which can be processed by a real 3D-CAD-system .

Forming steps calculated by COPRA
Forming steps calculated by COPRA

 

3) design of the drawing ring surface:
The different shapes calculated by COPRA are now connected with free form surfaces. To make that process as easy as possible this will be done by a program tailored to this job.
The result is a "negative" of the actual drawing ring.
Computer model of the negavtive drawing ring
Computer model of the negavtive drawing ring

 

4) design of the actual drawing ring
The calculated surfaces will now be subtracted from the cylinder building the actual drawing ring. The result is the final drawing ring with the surface necessary to make the shaped tube

Computer model of the final drawing ring
Computer model of the final drawing ring

 

M5 - COPRAź Professional Design Module for Drawing Rings (2D Part)
calculates the forming steps required to draw a tube into special shapes.
COPRA for Drawn Tubes is at the moment the only software available for this specific problem
It includes functions like:
Design of the final cross section (2D)
Calculation and design of individual forming steps (2D)

 

M6 - COPRAź Professional Design Module for Drawing Rings (3D Part)
calculates the forming steps required to draw a tube into special shapes.
COPRA for Drawn Tubes is at the moment the only software available for this specific problem
It includes functions like:
Design of the drawing ring surface
Design of the actual drawing ring
This COPRA software module requires Autodesk Mechanical Desktop (not included in this package)

 

System requirements
What are the requirements for a successful operation of COPRA ?
COPRA is available for  Windows operating systems and requires AutoCAD or Mechanical Desktop (both registered trademarks of Autodesk). AutoCAD is not included in the COPRA software unless you order a COPRA stand alone option.

 
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