Hi all,
I do appreciate in advance for your help. I have some files in formats mentioned in subject of this post which are free downloadable 3d models in GRABCAD websie. I need them to in auto cad 2013 or 2012 format (.dwg or dxf) or any other format like .iges so i can import them into auto cad. I've searched a bit on google to find a converter but I could not. So I am asking for a free converter or any body can save them as a cad file for me.

here is the links:

pipe
http://grabcad.com/library/hoover-pipe
http://grabcad.com/library/50-mm-twisted-tube-for-ventilation
http://grabcad.com/library/flexible-tube--2

cyclone
http://grabcad.com/library/sheetmetal-paper-trim-cyclone
http://grabcad.com/library/ciclone-cyclone

vacuum pump on cyclone
http://grabcad.com/library/vacuum-pump
http://grabcad.com/library/agni-motor-95r

motor
http://grabcad.com/library/motor-weg-324ts-esquerdo
http://grabcad.com/library/electric-motor-256t-frame
http://grabcad.com/library/gamak-100l-3kw-electric-motor

screw
http://grabcad.com/library/plastic-extrusion-screw
http://grabcad.com/library/extrusion-screw
http://grabcad.com/library/extruder-screw
http://grabcad.com/library/screw--21

tube as a barrel
http://grabcad.com/library/can-or-tube-for-reflex-suppressor

mold
http://grabcad.com/library/plastic-injection-mold--2
http://grabcad.com/library/unscrewing-mold
http://grabcad.com/library/plastic-mold-injection-1
http://grabcad.com/library/cover-mold
http://grabcad.com/library/mold-duas-placas

chair
http://grabcad.com/library/plastic-kiddies-chair

All the best.