Heat-sealing apparatus

A heat-sealing apparatus of the type comprising a bottom shell, an electric heating element fixedly mounted in said bottom shell near a front side of said bottom shell, and a top shell hinged to the bottom shell and adapted to press a loaded packing bag on said electric heating element for enabling the loaded packing bag to be sealed by heat, wherein said bottom shell comprises a top center recess, a through hole in said top center recess, a packing bag stretcher mounted in said top center recess and adapted to stretch open the mouth of the packing bag being loaded in said bottom shell, said packing bag stretcher comprising a bearing plate, said bearing plate having a vertical bottom rod inserted into said through hole in said top center recess, a compression spring sleeved onto the vertical bottom rod of said bearing plate and supported between said top center recess and said bearing plate, a press plate suspending above said bearing plate, said press plate having a transversely extended air hole, a suction tube extended from said air hole and connected to a vacuum pump installed in said bottom shell for enabling said vacuum pump to draw air out of the packing bag being loaded in said bottom shell, and two L-shaped clamping plates disposed at two sides of said bearing plate and adapted to clamp the mouth of the loaded packing bag on said press plate.