3D printer having dual stage structure

1. A 3D printer having a dual stage structure, the 3D printer comprising:

an extrusion unit comprising a nozzle configured to extrude a raw material;

a stacking base unit positioned under the extrusion unit and comprising a bed configured to receive the raw material on an upper surface thereof so that an object is formed in a layer-by-layer manner on the upper surface of the bed; and

a cutting unit between the stacking base unit and the extrusion unit and comprising a cutting tool configured to grind or cut the object formed on the upper surface of the bed, and

a frame positioned outside the extrusion unit, the cutting unit, and the stacking base unit,

wherein a distance between the extrusion unit and the cutting unit and a distance between the cutting unit and the bed are variable relative to each other

wherein the frame extends vertically and is configured to be connected to one or more of the extrusion unit, the cutting unit, and the bed, and

the one or more of the extrusion unit, the cutting unit, and the stacking base unit are configured to be vertically movable along the frame,

wherein the frame comprises:

an outer frame comprising a plurality of outer guide beams arranged in a circular shape; and

a rotatable frame comprising one or more rotatable guide beams arranged inside a circle formed by the outer guide beams,

wherein the cutting unit is configured to be connected to an inner side of the rotatable frame,

the rotatable guide beams are configured to extend vertically such that the cutting unit is vertically movable along the rotatable frame, and

the rotatable frame is configured to be rotatable inside the outer frame around a center of the circle formed by the outer guide beams such that the cutting unit is rotatable about the center,

wherein the rotatable frame further comprises a ring-shaped connection part configured to be connected to lower portions of the rotatable guide beams and to be concentric with the circle formed by the outer guide beams,

the outer frame further comprises a cylindrical connection part configured to connect lower portions of the outer guide beams and to be inserted into the ring-shaped connection part, and

the ring-shaped connection part is configured to be rotatable on the cylindrical connection part to rotate the rotatable frame.

2. The 3D printer of claim 1 , wherein the stacking base unit comprises a height adjusting device positioned under the bed on the cylindrical connection part and having a variable vertical length, and

the height adjusting device is configured to modify a height of the stacking base unit.

3. The 3D printer of claim 1 , wherein the stacking base unit further comprises a first jig having a certain area,

wherein the bed is on top of the first jig, and

a plurality of support holes are formed in the bed.

4. The 3D printer of claim 3 , wherein the bed comprises first to third build plates that have certain areas and are sequentially stacked,

the first to third build plates comprise first to third support holes, respectively, and

the first to third build plates are configured to be individually movable in a horizontal direction to align or misalign the first to third support holes in a vertical direction.

5. The 3D printer of claim 3 , further comprising a height adjusting device on a lower portion of the first jig and configured to vertically move the first jig.

6. The 3D printer of claim 5 , wherein the height adjusting device has a variable vertical length so as to vertically move the first jig and the bed.