Vacuum forming machine having pre-blowing lower chamber

A vacuum forming machine having a pre-blowing lower chamber and configured to vacuum form a raw material (1), the vacuum forming machine comprising:

• a sealing lower clamp (100a) configured to clamp a lower surface of an edge portion of the raw material (1);
• an upper clamp (100b) configured to clamp an upper surface of the edge portion of the raw material (1);
• a lower heater (200a) disposed at a lower side of the raw material (1) for heating the raw material (1);
• an upper heater (200b) disposed at an upper side of the raw material (1) for heating the raw material (1);
• a lower mold (300a) disposed at a at the lower side of the lower heater (200a);
• a lower chamber (400) disposed at a lower side of the raw material in which the lower heater (200a) and the lower mold (300a) are located, wherein an upper surface of the lower chamber (400) is closed by the raw material (1) and the sealing lower clamp (100a) and sealed such that air is prevented from leaking to the outside;
• a blowing device (500) configured to introduce a preset amount of air into the lower chamber (400) for limiting the raw material (1) from being thermally expanded and sagged in a heating process of the raw material (1);
• and
• a controller (800) configured to control an operation of the vacuum forming machine,
• wherein the sealing lower clamp (100a) comprises first, second, third, and fourth side plates (11, 12, 13, 14) to fit side surfaces of the raw material, and each of the first, second, third, and fourth side plates (11, 12, 13, 14) is configured to move in X and Y-axis directions to fit to the shape of the raw material, wherein a contact surface between the side plates and the raw material is sealed, and
• wherein the first, second, third, and fourth side plates (11, 12, 13, 14) comprise:
• lower plates (11a, 12a, 13a, 14a), respectively, that are configured to reciprocate, and
• upper plates (11b, 12b, 13b, 14b) located at upper sides of the lower plates (11a, 12a, 13a, 14a), and configured to operate in cooperation with the lower plates (11a, 12a, 13a, 14a), wherein the upper plates (11b, 12b, 13b, 14b) are configured to reciprocate in directions orthogonal to the lower plates (11a, 12a, 13a, 14a), and adjacent surfaces thereof are in close contact with each other.