Injection molding apparatus

1. An injection molding apparatus comprising;

an upper mold including a first plate, a first pair of plates arranged in a horizontal direction and each having an upper ends coupled to a lower surface of the first plate, and a cylinder penetrating through the first plate in a vertical direction so that a lower portion thereof protrudes downwardly of the first plate and ascending and descending;

a lower mold including a second plate spaced downwardly apart from the first plate by a predetermined distance, a second pair of plates arranged in the horizontal direction and each having a lower end coupled to an upper surface of the second plate and an upper end contacting a lower end of the first pair of plates, and an injection hole formed at a central portion of the second plate and having a melted resin injected therethrough;

a receive block disposed in parallel with the first plate and having a lower portion of the cylinder buried therein;

a fixed block interposed between the first pair of plates;

a movable block spaced downwardly apart from the fixed block by a predetermined interval, interposed between the first pair of plates or between the second pair of plates, and ascending and descending;

a variable cavity formed between the movable block and the upper and lower molds, filled with the melt resin injected from the injection hole, and having a size adjusted by the ascent and the descent of the movable block;

a movable block adjusting unit connecting the fixed block and the movable block to each other and adjusting the ascent and the descent of the movable block; and

an ejector pipe having an upper portion buried in the receive block, penetrating through the fixed block and the movable block in the vertical direction, and ascending or descends by the cylinder and the receive block to eject the melted resin solidified in the variable cavity to the outside.

2. The injection molding apparatus of claim 1 , further comprising an internal mold received in the variable cavity.

3. The injection molding apparatus of claim 2 , wherein the internal mold is formed in a rectangular shape.

4. The injection molding apparatus of claim 1 , wherein the movable block adjusting unit is a first spring connecting the fixed block and the movable block to each other.

5. The injection molding apparatus of claim 4 , wherein the first spring has an upper portion buried in the fixed block and a lower portion buried in the movable block.

6. The injection molding apparatus of claim 1 , wherein the movable block adjusting unit includes:

a screw screwed to the fixed block so that a lower portion thereof protrudes downwardly from the fixed block;

a screw handle coupled to an upper end of the screw;

a second spring wound around a lower circumference of the screw;

a shaft part formed in a sandglass shape and having an upper end coupled to a lower end of the screw; and

a suspending box having a lower portion of the shaft part rotatably inserted thereinto, and insertedly coupled into the movable block.

7. The injection molding apparatus of claim 6 , wherein the suspending box has a structure in which widths of a left surface and a right surface thereof in the horizontal direction become gradually narrower toward a downward direction.