Developing　a　clamping　device　fixed　directly　on　a　multi-degree　of　freedom　robot　manipulator　to　solve　the　problem　of　easy　deformation　of　sheet　metal　plates　in　three　dimensions　free　curve　is　still　very　challenging.　This　work　describes　the　conceptual　design,　the　mechanical　design,　and　the　design　of　control　system　of　a　new　clamping　device　for　the　free　curve　welding.　The　basic　function　of　the　clamping　device　is　to　provide　a　stable　and　adjustable　mechanical　pressure　which　is　generated　by　a　compressed　conventional　spring　to　a　sheet　plate　in　the　welding　process.　Following　the　concept　design　stage,　the　mechanical　design　is　performed,　aimed　at　effectively　controlling　the　deformation　of　sheet　metal　and　eliminating　the　gap　between　the　plates　in　the　welding　process.　Finally,　the　control　methodology　is　put　forward.　Thanks　to　the　proposed　modular　construction　and　the　use　of　a　conventional　spring,　the　device　shows　good　performances.　The　developed　clamping　device　can　also　be　extended　to　other　applications　in　surface　manufacturing　such　as　spray　painting　on　space　free　curve.　©　2015　SERSC.