Plastic sheet supplying apparatus for thermoforming machine having adjustable pin

A plastic sheet supplying apparatus for a thermoforming machine, which is adapted to adhere a plastic sheet to a base member, the apparatus comprising:

• a clamp unit in a loading step;
• a clamp unit in a molding step;
• a position adjustable pin fixing unit having a plurality of fixing pins arranged linearly to edge portions of a plastic sheet, each of the fixing pins supporting the plastic sheet received from an outside to fix the plastic sheet in horizontal arrangement, the fixing pins adapted to be moved with respect to one another in response to a degree of sagging or size change of the plastic sheet caused by heating of the plastic sheet;
• a plastic sheet heating unit arranged at a preset position, and heating the plastic sheet fixed to the position adjustable pin fixing unit;
• and
• a controller controlling operations of the position adjustable pin fixing unit and the plastic sheet heating unit,
• wherein the plurality of fixing pins are arranged at a lower side of the plastic sheet to support from the lower side of the plastic sheet, and the clamp unit in the loading step and the clamp unit in the molding step are arranged at an upper side of the plastic sheet, respectively, such that interferences between the fixing pins, the clamp unit in the loading step and the clamp unit in the molding step are prevented from occurring in a process of clamping and transferring the plastic sheet.