convert spline to polyline

I am having trouble with the company use to laser cut my kits, it appears that when I send my drawing in DXF or DWG format, the software they use for the laser cutter does not recognise any of the spline curves in my drawings, they have suggested converting the splines to polylines but I cant find anything in the Corel Draw x5 help section that tells me how to do this. can anyone shed any light on this issue, thanks