Merge of arcs creates circles

I am using LibreCAD for preparation of CAD files for software Vectric for generating of CNC codes.
So that I could use drilling processes I need all circles to be defined as circle. Nevertheless some CAD files generated by designer represent circle by two arc which has the geomtry of the circle together. Unfortunately I do not know any way how to  merge them into cyrcle. I just managed to merge them to polyline which does not work for Vectric. So I suggest to add function which merge all selected arcs with suitable geometry to circles.

well, in 2.2.2 alpha release we have similar functionality - the command is "Circle -> By Arc".

I'm not sure whether it's available in 2.2.1, however.  

With that command, the scenario is as follows:

1) Delete some arc (from 2 arcs circle)
2) invoke that command
3) make sure that the following settings are set (in Action's options toolbar) : Replace Arc - checked, Radius Shift = 0. As for setting pen and layer - that's up to you, where created circles will be located.
4) apply that command by selecting remaining arc.

After this operation, you may delete 1 arc for each place where your circle is represented by 2 arcs.

After that, select remaining arcs (as "By Arc" command handles not only single arc, but also entities, that are selected at the actions' invocation).

Invoke the command - and that's it.

You can find alpha build for 2.2.2 here:
 
https://github.com/LibreCAD/LibreCAD/releases/tag/2.2.2_alpha-latest

P.S merging arcs may be also interesting options - yet here we have to be sure that their coordinates are without gaps.

Could you please share a sample DXF with such representation of circles by arcs?

SKRINE_KONTEJNER.dxf

The circles in your drawing are constructed as semicircle ARC entities.

So the easiest way is to create a new layer for easy separation.
Then use Snap to Center, which will snap to the center of the arcs and create circles with the Circle/Radius tool.
The circles will exactly overlap the semicircles.
When all circles are created, make the circle layer invisible to delete the semicircles. If needed, move the circles from the new layer to their destination layer.

A separate tool for this would not be more efficient than the described workflow. It might even need some more steps to select and convert the arcs.
It will also be error prone when the composed circle is inaccurate with gaps, more than 2 arcs or diverting radii.

Armin