Try these tools.
cad2svg is a simple Linux command-line utility that automatically converts AutoCAD files (both dwg and dxf) to SVG
This link is not working anymore:
2) http://davinder.in/blog/how-install-libredwg-ubuntu
GNU LibreDWG is a free C library to handle DWG files.
Kabeja is a Java library for parsing, processing and converting Autodesk's DXF format
A dxf to svg converter.
Can be used to create pure svg files or Inkscape svg files with extra information like layers.