The present invention relates to a spindle drive. A spindle drive according to an exemplary embodiment of the present invention includes: a body that is disposed at a side of a machine tool; a spindle that is disposed at the body, with a ring gear disposed thereunder; a gear box that is disposed at a side of the body; a plurality of driven shafts that is disposed at the gear box and engaged with the ring gear; an idle shaft that is disposed at the gear box and engaged with a plurality of driven gears at a side; a high-speed driving shaft that is disposed at the gear box and drives the idle shaft while changing the speed by a driving force of a spindle motor; a low-speed driving gear that is disposed at the gear box, engaged with the driven shafts, and pressed by a pressing unit such that backlash is removed; a decelerator that is disposed at the low-speed driving gear and driven by a servomotor to drive the low-speed driving gear; and a clutch unit that is disposed between the servomotor and the low-speed driving gear and controls power transmission of the servomotor.
1. A spindle drive, comprising:
a body that is disposed at a side of a machine tool;
a spindle that is disposed at the body, with a ring gear disposed thereunder;
a gear box that is disposed at a side of the body;
a plurality of driven shafts that is disposed at the gear box and engaged with the ring gear;
an idle shaft that is disposed at the gear box and engaged with a plurality of driven gears at a side;
a high-speed driving shaft that is disposed at the gear box and drives the idle shaft while changing the speed by a driving force of a spindle motor;
a low-speed driving gear that is disposed at the gear box, engaged with the driven shafts, and pressed by a pressing unit such that backlash is removed;
a decelerator that is disposed at the low-speed driving gear and driven by a servomotor to drive the low-speed driving gear;
a clutch unit that is disposed between the servomotor and the low-speed driving gear and controls power transmission of the servomotor;
a first transmission driving gear that is disposed at the upper portion of the driving shaft;
a second transmission driving gear that is disposed at the lower portion of the driving shaft by a spline and linearly moves; and
a third transmission driving gear that is disposed at the driving shaft by a spline, linearly moves, and is engaged with the first transmission driving gear.
2. The spindle drive according to claim 1 , comprising:
an actuator that is disposed at a side of the gear box and moves the second transmission driving gear and the third transmission driving gear to predetermined positions;
a first transmission driven gear 34 a that is disposed at the upper portion of the idle shaft and engaged with the first transmission driving gear; and
a second transmission driven gear that is disposed at the lower portion of the idle shaft and engaged with the second transmission driving gear.
3. The spindle drive according to claim 2 , wherein the predetermined positions are a high-speed position where the first transmission driving gear and the third transmission driving gear are engaged and the second transmission driving gear and the second transmission driven gear are disengaged such that high-speed power is transmitted,
a neutral position where the first transmission driving gear and the third transmission driving gear are disengaged and the second transmission driving gear and the second transmission driven gear are disengaged such that power is not transmitted; and
a low-speed position where the first transmission driving gear and the third transmission driving gear are disengaged and the second transmission driving gear and the second transmission driven gear are engaged such that low-speed power is transmitted.
4. The spindle drive according to claim 1 , wherein in the pressing unit, a cylinder chamber is formed at a side of the gear box, an up-down movable shaft is disposed in the cylinder chamber, and the low-speed driving gear is disposed under the up-down movable shaft, such that the up-down movable shaft is moved down by hydraulic pressure supplied to the chamber and presses the low-speed driving gear.
5. The spindle drive according to claim 1 , wherein in the clutch unit, a first curvic coupling gear is formed at the lower end of the up-down movable shaft, a second curvic coupling gear is formed at the lower end of the low-speed driving gear, a third curvic coupling gear is formed at the upper portion, apart from the low-speed driving gear, and a curvic coupling member that is moved up/down by hydraulic pressure is disposed, such that the third curvic coupling gear and the first and second curvic coupling gears and can be engaged or disengaged by the up-down movement of the curvic coupling member, thus controlling power transmission.