Cover sheet supply apparatus having variable clamp for thermoforming machine

A cover sheet supply apparatus for a thermoforming machine, the thermoforming machine including a heating unit for heating the cover sheet to be adhered to a target object, the cover sheet supply apparatus comprising:

• a support frame (100);
• a pair of longitudinal guides (200) disposed in the support frame (100) at positions spaced apart from each other, each of the longitudinal guides (200) comprising a longitudinal rail (210), with a longitudinal fixed unit (220) fixed to a medial area of the longitudinal rail (210);
• a pair of lateral guides (300) disposed in the support frame (100) at positions spaced apart from each other and on opposite sides of the longitudinal guides (200), each of the lateral guides (300) comprising a lateral rail (310), with a lateral fixed unit (320) fixed to a medial area of the lateral rail (310);
• a plurality of longitudinal movable clamps (230) installed on each of the longitudinal rails (210) to clamp the cover sheet at multiple locations with the longitudinal movable clamps (230), the longitudinal movable clamps (230) being successively connected to one another by a longitudinal link (400) from the medially-located longitudinal fixed unit (220) and to the lateral guides (300);
• a plurality of lateral movable clamps (330) installed on each of the lateral rails (310) to clamp the cover sheet at multiple locations with the lateral movable clamps (330), the lateral movable clamps (330) being successively connected to one another by a lateral link (500) from the medially-located lateral fixed unit (320) and to the longitudinal guides (200);
• a lateral moving means (600) configured to move the longitudinal guides (200) toward and away from each other in a lateral direction, and thereby allowing the lateral movable clamps (330) to expand equidistantly along the lateral rails (310) in response to an away movement of the longitudinal guides (200) to stretch the cover sheet with the multiple lateral movable clamps (330) as the cover sheet is heated and expanded by the heating unit;
• and
• a longitudinal moving means (700) configured to move the lateral guides (300) toward and away from each other in a longitudinal direction, and thereby allowing the longitudinal movable clamps (230) to expand equidistantly along the longitudinal rails (210) in response to an away movement of the lateral guides (300) to stretch the cover sheet with the multiple longitudinal movable clamps (230) as the cover sheet is heated and expanded by the heating unit.